We analyze the possibility of producing two color X or γ radiation by Thomson/Compton back-scattering between a high intensity laser pulse and a two-energy level electron beam, constituted by a couple of beamlets separated in time and/or energy obtained by a photoinjector with comb laser techniques and linac velocity bunching. The parameters of the Thomson source at SPARC_LAB have been simulated, proposing a set of values for a realistic experiments.

We analyze the possibility of producing two-color x or γ radiation by Thomson/Compton backscattering between a high intensity laser pulse and a two-energy level electron beam, constituted by a couple of beamlets separated in time and/or energy obtained by a photoinjector with comb laser techniques and linac velocity bunching. The parameters of the Thomson source at SPARC_LAB have been simulated, proposing a set of realistic experiments.

The objective of this work is to design, build, and fly a dual-purpose payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field to protect manned spacecraft against particle radiation. An additional mission objective is to study the effect of this moving field on upper atmosphere plasmas. Both mission objectives appear to be capable of being tested using the same superconducting coil. The potential benefits of this magnetic shield concept apply directly to both earth-orbital and interplanetary missions. This payload would be a first step in assessing the true potential of large volume magnetic fields in the U.S. space program. Either converted launch systems or piggyback payload opportunities may be appropriate for this mission. The use of superconducting coils for magnetic shielding against solar flare radiation during manned interplanetary missions has long been contemplated and was considered in detail in the years preceding the Apollo mission. With the advent of new superconductors, it has now become realistic to reconsider this concept for a Mars mission. Even in near-earth orbits, large volume magnetic fields produced using conventional metallic superconductors allow novel plasma physics experiments to be contemplated. Both deployed field-coil and non-deployed field-coil shielding arrangements have been investigated, with the latter being most suitable for an initial test payload in a polar orbit.

A dual-channel telescope allows for a wide-field telescope design wit h a good, narrow field channel of fewer surfaces for shorter-wavelen gth or planet-finding applications. The design starts with a Korsch three-mirror-anastigmat (TMA) telescope that meets the mission criter ia for image quality over a wide field of view. The internal image a t the Cassegrain focus is typically blurry due to the aberration bala ncing among the three mirrors. The Cassegrain focus is then re-optim ized on the axis of the system where the narrow field channel instru ment is picked off by bending the primary mirror.

The utilisation of dual-purpose crops, especially wheat and canola grown for forage and grain production in sheep-grazing systems, is reviewed. When sown early and grazed in winter before stem elongation, later-maturing wheat and canola crops can be grazed with little impact on grain yield. Recent research has sought to develop crop- and grazing-management strategies for dual-purpose crops. Aspects examined have been grazing effects on crop growth, recovery and yield development along with an understanding of the grazing value of the crop fodder, its implications for animal nutrition and grazing management to maximise live-weight gain. By alleviating the winter 'feed gap', the increase in winter stocking rate afforded by grazing crops allows crop and livestock production to be increased simultaneously on the same farm. Integration of dual-purpose wheat with canola on mixed farms provides further systems advantages related to widened operational windows, weed and disease control and risk management. Dual-purpose crops are an innovation that has potential to assist in addressing the global food-security challenge.

The analysis presented in this report investigated how the direct disposal of dualpurpose canisters (DPCs) may be affected by the use of standard transportation aging and disposal canisters (STADs), early or late start of the repository, and the repository emplacement thermal power limits. The impacts were evaluated with regard to the availability of the DPCs for emplacement, achievable repository acceptance rates, additional storage required at an interim storage facility (ISF) and additional emplacement time compared to the corresponding repackaging scenarios, and fuel age at emplacement. The result of this analysis demonstrated that the biggest difference in the availability of UNF for emplacement between the DPC-only loading scenario and the DPCs and STADs loading scenario is for a repository start date of 2036 with a 6 kW thermal power limit. The differences are also seen in the availability of UNF for emplacement between the DPC-only loading scenario and the DPCs and STADs loading scenario for the alternative with a 6 kW thermal limit and a 2048 start date, and for the alternatives with a 10 kW thermal limit and 2036 and 2048 start dates. The alternatives with disposal of UNF in both DPCs and STADs did not require additional storage, regardless of the repository acceptance rate, as compared to the reference repackaging case. In comparison to the reference repackaging case, alternatives with the 18 kW emplacement thermal limit required little to no additional emplacement time, regardless of the repository start time, the fuel loading scenario, or the repository acceptance rate. Alternatives with the 10 kW emplacement thermal limit and the DPCs and STADs fuel loading scenario required some additional emplacement time. The most significant decrease in additional emplacement time occurred in the alternative with the 6 kW thermal limit and the 2036 repository starting date. The average fuel age at emplacement ranges from 46 to 88 years. The maximum fuel age at

A source book on nuclear dual-purpose electric/distillation desalination plants was prepared to assist government and other planners in preparing broad evaluations of proposed applications of dual-purpose plants. The document is divided into five major sections. Section 1 presents general discussions relating to the benefits of dual-purpose plants, and spectrum for water-to-power ratios. Section 2 presents information on commercial nuclear plants manufactured by US manufacturers. Section 3 gives information on distillation desalting processes and equipment. Section 4 presents a discussion on feedwater pretreatment and scale control. Section 5 deals with methods for coupling the distillation and electrical generating plants to operate in the dual mode.

Purpose: Spectral information of the output of x-ray tubes in (dual source) computer tomography (CT) scanners can be used to improve the conversion of CT numbers to proton stopping power and can be used to advantage in CT scanner quality assurance. The purpose of this study is to design, validate, and apply a compact portable Compton spectrometer that was constructed to accurately measure x-ray spectra of CT scanners. Methods: In the design of the Compton spectrometer, the shielding materials were carefully chosen and positioned to reduce background by x-ray fluorescence from the materials used. The spectrum of Compton scattered x-rays alters from the original source spectrum due to various physical processes. Reconstruction of the original x-ray spectrum from the Compton scattered spectrum is based on Monte Carlo simulations of the processes involved. This reconstruction is validated by comparing directly and indirectly measured spectra of a mobile x-ray tube. The Compton spectrometer is assessed in a clinical setting by measuring x-ray spectra at various tube voltages of three different medical CT scanner x-ray tubes. Results: The directly and indirectly measured spectra are in good agreement (their ratio being 0.99) thereby validating the reconstruction method. The measured spectra of the medical CT scanners are consistent with theoretical spectra and spectra obtained from the x-ray tube manufacturer. Conclusions: A Compton spectrometer has been successfully designed, constructed, validated, and applied in the measurement of x-ray spectra of CT scanners. These measurements show that our compact Compton spectrometer can be rapidly set-up using the alignment lasers of the CT scanner, thereby enabling its use in commissioning, troubleshooting, and, e.g., annual performance check-ups of CT scanners.

A presentation is made of five award-winning designs for a fireproof community recreation facility, on a selected site in New York City, incorporating a fallout shelter as a dual-purpose space. Graphic illustrations are given of the award winning designs, each of which used one of the following solutions--(1) the fallout structure above grade with…

Dakota Trailblazer, a new, full-season, dual-purpose cultivar was released in 2009 by the North Dakota Agricultural Experiment Station. It has medium russet skin, white to creamy flesh, and long and blocky tuber type. Dakota Trailblazer originated from the cross of A89163-3LS x A8914-4, parental s...

A dualpurpose optical instrument is described capable of simultaneously acting as a spectrometer and diffractometer to respectively perform elemental and structural analysis of an unknown sample. The diffractometer portion of the instrument employs a modified form of Seeman-Bohlin focusing which involves providing a line source of X-rays, a sample, and a detector, all on the same focal circle. The spectrometer portion of the instrument employs a fixedly mounted X-ray energy detector mounted outside of the plane of the focal circle.

The study of Compton scattering—S + γ → S + γ—at MAMI and elsewhere has led to a relatively successful understanding of proton structure via its polarizabilities. The recent observation of gravitational radiation observed by LIGO has raised the need for a parallel understanding of gravitational Compton scattering—S + g → S + g—and we show here how it can be obtained from ordinary Compton scattering by use of the double copy theorem.

The aim of the study was to estimate the genetic parameters for five composite traits and 20 individual type traits on 10,735 first-parity Rendena dual-purpose cows. Fixed effects included in the linear animal mixed models were herd-year-classifier, days in milk and age at first calving; the additive genetic effect of the animal was included as a random effect. Heritability estimates varied from 0.12 (feet) to 0.52 (stature). Genetic correlations between the individual body size traits were all ≥0.69; similar strong genetic correlations existed between traits describing similar morphological characteristics (e.g. mammary system, fleshiness). Many of the body size traits were negatively genetically correlated with animal fleshiness. Genetic trends showed that genetic merit for body size increased consistently over the last 10 years, while genetic merit for fleshiness declined. These results suggest that the characteristics of the dual-purpose Rendena cattle are becoming more like specialized milk-producing animals. Nonetheless, sufficient genetic variation exists to halt or reverse the deterioration in fleshiness.

The Compton Observatory Science Workshop was held in Annapolis, Maryland on September 23-25, 1991. The primary purpose of the workshop was to provide a forum for the exchange of ideas and information among scientists with interests in various areas of high energy astrophysics, with emphasis on the scientific capabilities of the Compton Observatory. Early scientific results, as well as reports on in-flight instrument performance and calibrations are presented. Guest investigator data products, analysis techniques, and associated software were discussed. Scientific topics covered included active galaxies, cosmic gamma ray bursts, solar physics, pulsars, novae, supernovae, galactic binary sources, and diffuse galactic and extragalactic emission.

NASA missions and space exploration rely on strong, ultra lightweight materials. Such materials are needed for building up past and present space vehicles such as the Sojourner Rover (1997) or the two MERs (2003), but also for a number of components and/or systems including thermal insulators, Solar Sails, Rigid Aeroshells, and Ballutes. The purpose of my internship here at Glenn Research Center is to make dualpurpose materials; materials that in addition to being lightweight have electronic, photophysical and magnetic properties and, therefore, act as electronic components and sensors as well as structural components. One type of ultra lightweight material of great interest is aerogels, which have densities ranging from 0.003 g/cc to 0.8 g/cc . However, aerogels are extremely fragile and, as a result, have limited practical applications. Recently, Glenn Research Center has developed a process of nano-casting polymers onto the inorganic network of silica-based aerogels increasing the strength 300 fold while only increasing the density 3 fold. By combining the process of nano-casting polymers with inorganic oxide networks other than silica, we are actively pursuing lightweight dualpurpose materials. To date, thirty different inorganic oxide aerogels have been prepared using either standard sol-gel chemistry or a non-alkoxide method involving metal chloride precursors and an epoxide; epichlorohydrin, propylene oxide or trimethylene oxide, as proton scavengers. More importantly, preliminary investigations show that the residual surface hydroxyl groups on each of these inorganic oxide aerogels can be successfully crosslinked with urethane. In addition to characterizing physical and mechanical properties such as density, strength and flexibility, each of these metal oxide aerogels are being characterized for thermal and electronic conductivity and magnetic and optical properties.

Genealogy and productive information of 48621 dual-purpose buffaloes born in Colombia between years 1996 and 2014 was used. The following traits were assessed using one-trait models: milk yield at 270 days (MY270), age at first calving (AFC), weaning weight (WW), and weights at the following ages: first year (W12), 18 months (W18), and 2 years (W24). Direct additive genetic and residual random effects were included in all the traits. Maternal permanent environmental and maternal additive genetic effects were included for WW and W12. The fixed effects were: contemporary group (for all traits), sex (for WW, W12, W18, and W24), parity (for WW, W12, and MY270). Age was included as covariate for WW, W12, W18 and W24. Principal component analysis (PCA) was conducted using the genetic values of 133 breeding males whose breeding-value reliability was higher than 50% for all the traits in order to define the number of principal components (PC) which would explain most of the variation. The highest heritabilities were for W18 and MY270, and the lowest for AFC; with 0.53, 0.23, and 0.17, respectively. The first three PCs represented 66% of the total variance. Correlation of the first PC with meat production traits was higher than 0.73, and it was -0.38 with AFC. Correlations of the second PC with maternal genetic component traits for WW and W12 were above 0.75. The third PC had 0.84 correlation with MY270. PCA is an alternative approach for analyzing traits in dual-purpose buffaloes and reduces the dimension of the traits. PMID:26230093

Factor analysis was applied to individual type traits (TT) scored in primiparous cows belonging to two dualpurpose Italian breeds, Rendena (REN; 20 individual type traits evaluated on 11 399 first parity cows), and Aosta Red Pied (ARP; 22 individual type traits evaluated on 36 168 primiparous cows). Six common latent factors (F1 to F6; eigenvalues ⩾1) which explained 63% (REN) and 58% (ARP) of the total variance were obtained. F1 included TT mainly related to muscularity, and F2 to body size. The F3 and F4 accounted for udder size and conformation, respectively. F5 included rear legs and feet. Biological significance for F6 was not readily obtained. Moderate to low heritability were estimated through REML single-trait analysis from factor scores (from 0.22 to 0.52 in REN, and from 0.08 to 0.37 in ARP). The greatest heritability values were estimated for body size and muscularity (0.52 and 0.37 for body size; and 0.40 and 0.32 for muscularity in REN and ARP, respectively). As expected, rank correlations, obtained considering estimated breeding values derived from best linear unbiased prediction analysis on the individual TT and factor score, showed similar coefficients to those observed in the factor analysis following loading of TT within each latent factor. These results suggest the possibility to implement the factor analysis in the morphological evaluation, simplifying the information given by the type traits into new variables useful for the genetic improvement of dualpurpose cattle.

The aim of this study was to assess the energetic efficiency of milk synthesis by grazing dual-purpose cows with or without a starch-based supplement in tropical South Mexico. Forty-six Holstein × Zebu cows were used in a 2 × 2 × 2 factorial design. Factors analysed were diet (supplemented, unsupplemented), age (young: 1-2 calvings, mature: >3 calvings) and day of lactation (21 and 84 days post-calving). The supplement represented about 30% of estimated dry matter (DM) intake. Grass intake was measured using the n-alkane technique at 21 and 84 days post-calving when calculations of efficiency were performed. Efficiency for milk synthesis was reported as feed conversion efficiency (FCE, kilograms of milk per kilogram of DM intake), gross energetic efficiency (GEE, milk energy output/metabolisable energy (ME) intake) and efficiency of ME use for lactation (k(l), adjusted to zero energy balance). There were no interactions between factors. FCE and GEE were not different between diets, but supplemented cows had a lower (p Dual-purpose cows used tropical grasses efficiently for milk synthesis, and higher milk yield observed in supplemented cows was due to a higher intake of nutrients rather than a higher energetic efficiency.

Research on domestic animals (cattle, swine, sheep, goats, poultry, horses, and aquatic species) at land grant institutions is integral to improving the global competitiveness of US animal agriculture and to resolving complex animal and human diseases. However, dwindling federal and state budgets, years of stagnant funding from USDA for the Competitive State Research, Education, and Extension Service National Research Initiative (CSREES-NRI) Competitive Grants Program, significant reductions in farm animal species and in numbers at land grant institutions, and declining enrollment for graduate studies in animal science are diminishing the resources necessary to conduct research on domestic species. Consequently, recruitment of scientists who use such models to conduct research relevant to animal agriculture and biomedicine at land grant institutions is in jeopardy. Concerned stakeholders have addressed this critical problem by conducting workshops, holding a series of meetings with USDA and National Institutes of Health (NIH) officials, and developing a white paper to propose solutions to obstacles impeding the use of domestic species as dual-purpose animal models for high-priority problems common to agriculture and biomedicine. In addition to shortfalls in research support and human resources, overwhelming use of mouse models in biomedicine, lack of advocacy from university administrators, long-standing cultural barriers between agriculture and human medicine, inadequate grantsmanship by animal scientists, and a scarcity of key reagents and resources are major roadblocks to progress. Solutions will require a large financial enhancement of USDA's Competitive Grants Program, educational programs geared toward explaining how research using agricultural animals benefits both animal agriculture and human health, and the development of a new mind-set in land grant institutions that fosters greater cooperation among basic and applied researchers. Recruitment of

We propose a class of AdS/CFT dual pairs which have small internal dimensions on the gravity side. Starting from known Freund-Rubin AdS/CFT dual pairs, we use 7-branes to nearly cancel the curvature energy of the internal dimensions while maintaining their stabilization. This leads to a new corner of the landscape - a class of AdS solutions with a hierarchically large AdS radius - with a dual field theory given (implicitly) by the infrared limit of a concrete brane construction involving D3-branes, 7-branes, and curvature. We first construct a class of hierarchical AdS5/CFT4 dual pairs with a simple formula for the number of degrees of freedom which we interpret in the dual QFT. We then generalize these to AdS4/CFT3 duals, and suggest extensions of the method to obtain de Sitter solutions.

A Compton tomography system comprises an x-ray source configured to produce a planar x-ray beam. The beam irradiates a slice of an object to be imaged, producing Compton-scattered x-rays. The Compton-scattered x-rays are imaged by an x-ray camera. Translation of the object with respect to the source and camera or vice versa allows three-dimensional object imaging.

Genetic and phenotypic parameters were estimated for dagginess, breech, wool, and fiber traits from approximately 29,500 progeny born in 2009 and 2010 in New Zealand dual-purpose ram breeding sheep flocks. Dagginess is adherence of fecal matter to the wool, and this study investigates the genetic and phenotypic correlations between dagginess and breech and wool traits. Estimates for heritability were moderate (0.21 to 0.44) for the following traits: dag score at 3 and 8 mo (DAG3, DAG8), breech bareness, wool length, wool bulk (BULK), mean fiber diameter, mean fiber diameter SD, mean fiber diameter CV, curvature (CURV), weaning weight at 3 mo, and autumn BW. Heritability estimates for fleece weight at 12 mo and proportion of medullated fibers were high (0.49 and 0.53, respectively). Dag score at 3 mo and DAG8 had low genetic and phenotypic correlations with all traits. Breech bareness had positive genetic and phenotypic correlations with CURV and BULK and mostly negative genetic correlations with all other wool traits. In summary the quantity and attributes of wool were not primary causative factors in fecal accumulation, leaving fecal consistency and composition as the major factors.

Using pedigree data, the inbreeding coefficients of 715 Austrian dual-purpose Simmental (Fleckvieh) bulls stationed in two artificial insemination (AI) centres in Upper and Lower Austria were calculated and incorporated in statistical models for the analysis of semen quality. Five semen quality parameters (volume, concentration, motility, number of spermatozoa per ejaculate and percentage of viable spermatozoa) of approximately 30,000 ejaculates, used in two separate data sets, were investigated. The mixed model included the fixed effects age class of the bull, bull handler, semen collector, month and year of collection, number of collection per bull and day, time interval since last collection, the linear continuous effect of the inbreeding coefficient of the bull, interactions between age class and month, and age class and interval since last collection, respectively, as well as the random effect of the bull and the random residual effect. Non-linear effects of inbreeding were significant for motility only. Despite the quite low inbreeding coefficients (mean 1.3%), all semen quality traits showed inbreeding depression, in four of the five traits significantly in at least one of the data sets. The magnitude of inbreeding depression was small, which might partly be caused by the low inbreeding levels and a potential pre-selection of the bulls in the AI centres. However, monitoring of inbreeding depression on fertility traits is recommended to avoid unrecognized deterioration of such traits.

Winter wheat (Triticum aestivum L.) cultivars which gain broad commercial acceptance in Oklahoma and surrounding states of the U.S. southern Great Plains must produce a definitive grain yield advantage, and they must demonstrate season-long dependability in dualpurpose management systems, effective...

A survey was carried out on 79 lactating Bos taurus/indicus cross-bred cows on three dual-purpose cattle farms to measure the blood concentration of metabolites and to evaluate possible relationships with nutritional status and productive variables. A rotational grazing system on Star grass and other tropical pastures (10-12% CP in leaves) was used and 2-3 kg/cow/day of concentrate were fed on two farms. Restricted calf suckling was used in two herds. Average milk yield sold per farm was 6 kg/day/cow and body condition scores (BCS) were between 3.0 and 3.8 on a scale of one-to-five. On two farms, the average interval from calving to conception (ICC) was more than 145 days. Mean blood concentrations of albumin, globulin, urea, beta-hydroxybutyrate and phosphorus were generally within reference values, but a significant group of cows had low levels of albumin and urea and high levels of globulin. Packed cell volume (PCV) was below normal values, with anemia in 63% of cows during the second trimester of lactation, which was negatively correlated to milk yield. The high incidence of anemia could be related to factors such as hematophagic parasites, not evaluated in this study. ICC values were negatively related to albumin level and could be associated with protein deficiency in the diet or with disease, as globulin values were high in many cows. Based on these diagnoses, an experiment was carried out on one of the farms to evaluate the influence of supplementation with 0.5 kg/cow/day of fish meal. Total milk yield was not influenced by the fish meal and reproductive efficiency was high in the two supplemental treatments. It was shown that supplementation with undergraded protein is not required in these cows.

The effect of including 9 % of molasses in supplements offered to dualpurpose cows, during dry season in subtropical Mexico was determined. Forage availability in pastures during the dry season is reduced and of low quality. Molasses is a readily available source of energy that may improve forage utilization and could have a positive effect on cow's milk production and calves daily weight gain (CDWG). Twelve multiparous Brown Swiss cows (409 ± 33 kg of body weight and 136 ± 73 days in milk), and their calves were randomly assigned to two supplements (six cows per treatment). Control supplement (COS) consisted of cracked maize ears (CME), soybean meal and urea (14 % CP), and experimental supplement in which 9 % of CME was replaced by molasses (MOS). Cows received 4.5 kg/cow/day dry matter (DM) of supplement. Experiment lasted 10 weeks divided in five experimental periods (EP). Animal responses (milk yield, milk composition, body weight, body condition score and CDWG) were recorded at the end of every EP. A linear mixed model was used to analyse the data as a complete random design. Net profits from milk and beef due to supplements were estimated using partial budget approach. Average milk yield was 7 (kg/cow/day) with 30.6, 30.4 and 42.5 (g/kg milk) of fat, protein and lactose, respectively. Average cow weight was 422 kg and CDWG was 0.8 kg/day. No significant responses on animal production variables were found when 9 % of MOS was included in the supplement; however, total net income increased on 4 %, due to higher CDWG.

Available in abstract form only. Full text of publication follows: In recent ten years a new technology of management of irradiated nuclear fuel (SNF) at the final stage of fuel cycle has been intensely developing on a basis of a new type of casks used for interim storage of SNF and subsequent transportation therein to the place of processing, further storage or final disposal. This technology stems from the concept of a protective cask which provides preservation of its content (SNF) and fulfillment of all other safety requirements for storage and transportation of SNF. Radiation protection against emissions and non-distribution of activity outside the cask is ensured by physical barriers, i.e. all-metal or composite body, shells, inner cavities for irradiated fuel assemblies (SFA), lids with sealing systems. Residual heat release of SFA is discharged to the environment by natural way: through emission and convection of surrounding air. By now more than 100 dualpurpose packaging sets TUK-108/1 are in operation in the mode of interim storage and transportation of SNF from decommissioned nuclear powered submarines (NPS). In accordance with certificate, spent fuel is stored in TUK-108/1 on the premises of plants involved in NPS dismantlement for 2 years, whereupon it is transported for processing to PO Mayak. At one Far Eastern plant Zvezda involved in NPS dismantlement there arose a complicated situation due to necessity to extend period of storage of SNF in TUK- 108/1. To ensure safety over a longer period of storage of SNF in TUK-108/1 it is essential to modify conditions of storage by removing of residual water and filling the inner cavity of the cask with an inert gas. Within implementation of the international 1.1- 2 project Development of drying technology for the cask TUK-108/1 intended for naval SNF under the Program, there has been developed the technology of preparation of the cask for long-term storage of SNF in TUK-108/1, the design of a mobile TUK-108

In Japan, the first Interim Storage Facility of spent nuclear fuel away from reactor site is being planned to start its commercial operation around 2010, in use of dual-purpose metal cask in the northern part of Main Japan Island. Business License Examination for safety design approval has started since March, 2007. To demonstrate the more scientific and rational performance of safety regulation activities on each phase for the first license procedure, CREPEI has executed demonstration tests with full scale casks, such as drop tests onto real targets without impact limiters(1) and seismic tests subjected to strong earthquake motions(2). Moreover, it is important to develop the knowledge for the inherent security of metal casks under extreme mechanical-impact conditions, especially for increasing interest since the terrorist attacks from 11th September 2001(3)-(6). This paper presents dynamic mechanical behavior of the metal cask lid closure system caused by direct aircraft engine crash and describes calculated results (especially, leak tightness based on relative dynamic displacements between metallic seals). Firstly, the local penetration damage of the interim storage facility building by a big passenger aircraft engine crash (diameter 2.7m, length 4.3m, weight 4.4ton, impact velocity 90m/s) has been examined. The reduced velocity is calculated by the local damage formula for concrete structure with its thickness of 70cm. The load vs. time function for this reduced velocity (60m/s) is estimated by the impact analysis using Finite Element code LS-DYNA with the full scale engine model onto a hypothetically rigid target. Secondly, as the most critical scenarios for the metal cask, two impact scenarios (horizontal impact hitting the cask and vertical impact onto the lid metallic seal system) are chosen. To consider the geometry of all bolts for two lids, the gasket reaction forces and the inner pressure of the cask cavity, the detailed three dimensional FEM models are

Economic values of clinical mastitis, claw disease, and feed efficiency traits along with 16 additional production and functional traits were estimated for the dairy population of the Slovak Pinzgau breed using a bioeconomic approach. In the cow-calf population (suckler cow population) of the same breed, the economic values of feed efficiency traits along with 15 further production and functional traits were calculated. The marginal economic values of clinical mastitis and claw disease incidence in the dairy system were -€ 70.65 and -€ 26.73 per case per cow and year, respectively. The marginal economic values for residual feed intake were -€ 55.15 and -€ 54.64/kg of dry matter per day for cows and breeding heifers in the dairy system and -€ 20.45, -€ 11.30, and -€ 6.04/kg of dry matter per day for cows, breeding heifers, and fattened animals in the cow-calf system, respectively, all expressed per cow and year. The sums of the relative economic values for the 2 new health traits in the dairy system and for residual feed intake across all cattle categories in both systems were 1.4 and 8%, respectively. Within the dairy production system, the highest relative economic values were for milk yield (20%), daily gain of calves (20%), productive lifetime (10%), and cow conception rate (8%). In the cow-calf system, the most important traits were weight gain of calves from 120 to 210 d and from birth to 120 d (19 and 14%, respectively), productive lifetime (17%), and cow conception rate (13%). Based on the calculation of economic values for traits in the dual-purpose Pinzgau breed, milk production and growth traits remain highly important in the breeding goal, but their relative importance should be adapted to new production and economic conditions. The economic importance of functional traits (especially of cow productive lifetime and fertility) was sufficiently high to make the inclusion of these traits into the breeding goal necessary. An increased interest

When a relativistic electron beam interacts with a high-field laser beam, intense and highly collimated electromagnetic radiation will be generated through Compton scattering. Through relativistic upshifting and the relativistic Doppler effect, highly energetic polarized photons are radiated along the electron beam motion when the electrons interact with the laser light. For example, X-ray radiation can be obtained when optical lasers are scattered from electrons of tens-of-MeV beam energy. Because of the desirable properties of the radiation produced, many groups around the world have been designing, building, and utilizing Compton sources for a wide variety of purposes. In this review article, we discuss the generation and properties of the scattered radiation, the types of Compton source devices that have been constructed to date, and the prospects of radiation sources of this general type. Due to the possibilities of producing hard electromagnetic radiation in a device that is small compared to the alternative storage ring sources, it is foreseen that large numbers of such sources may be constructed in the future.

The aim of this study was to identify if genomic variations associated with fatty acid (FA) composition are similar between the Holstein-Friesian (HF) and native dual-purpose breeds used in the Dutch dairy industry. Phenotypic and genotypic information were available for the breeds Meuse-Rhine-Yssel (MRY), Dutch Friesian (DF), Groningen White Headed (GWH), and HF. First, the reliability of genomic breeding values of the native Dutch dual-purpose cattle breeds MRY, DF, and GWH was evaluated using single nucleotide polymorphism (SNP) effects estimated in HF, including all SNP or subsets with stronger associations in HF. Second, the genomic variation of the regions associated with FA composition in HF (regions on Bos taurus autosome 5, 14, and 26), were studied in the different breeds. Finally, similarities in genotype and allele frequencies between MRY, DF, GWH, and HF breeds were assessed for specific regions associated with FA composition. On average across the traits, the highest reliabilities of genomic prediction were estimated for GWH (0.158) and DF (0.116) when the 8 to 22 SNP with the strongest association in HF were included. With the same set of SNP, GEBV for MRY were the least reliable (0.022). This indicates that on average only 2 (MRY) to 16% (GWH) of the genomic variation in HF is shared with the native Dutch dual-purpose breeds. The comparison of predicted variances of different regions associated with milk and milk fat composition showed that breeds clearly differed in genomic variation within these regions. Finally, the correlations of allele frequencies between breeds across the 8 to 22 SNP with the strongest association in HF were around 0.8 between the Dutch native dual-purpose breeds, whereas the correlations between the native breeds and HF were clearly lower and around 0.5. There was no consistent relationship between the reliabilities of genomic prediction for a specific breed and the correlation between the allele frequencies of this breed

The University of Florida Cooperative Extension conducted a statewide program with a dual role during 2013 and 2014 to enhance efficiency. The program provided in-service training to county Extension agents and provided continuing education to meet requirements needed by licensed pesticide applicators. Using Polycom distance technology, the event…

In 2011, we wrote a review for summarizing the phytochemical analysis (2006-2010) of medicine and food dualpurposes plants used in China (Zhao et al., J. Chromatogr. A 1218 (2011) 7453-7475). Since then, more than 750 articles related to their phytochemical analysis have been published. Therefore, an updated review for the advanced development (2011-2014) in this topic is necessary for well understanding the quality control and health beneficial phytochemicals in these materials, as well as their research trends.

Compton γ-ray imaging is inherently based on the assumption of γ-rays scattering with free electrons. In reality, the non-zero momentum of target electrons bound in atoms blurs this ideal scattering response in a process known as Doppler broadening. The design and understanding of advanced Compton telescopes, thus, depends critically on the ability to accurately account for Doppler broadening effects. For this purpose, a Monte Carlo package that simulates detailed Doppler broadening has been developed for use with the powerful, general-purpose GEANT3 and GEANT4 radiation transport codes. This paper describes the design of this package, and illustrates results of comparison with selected experimental data.

Dual X-ray absorptiometry is widely used in analyzing body composition and imaging. Both the method and its limitations are related to the Compton and photoelectric contributions to the X-ray attenuation coefficients of materials.

The slaughter and meat quality traits of 20-month-old wool (Merino), dual-purpose (Dohne Merino and South African Mutton Merino [SAMM]) and mutton (Dormer) type sheep were compared. Average live weights of SAMM and Dormer sheep were 23% heavier than those of Dohne Merinos which were 28% heavier than Merinos. Fat depths at the thirteenth rib and lumbar regions of Merino and Dohne Merino sheep were lower than those of SAMM and Dormer sheep. The cooking loss, drip loss and shearing value from the M. longissimus dorsi did not differ between breeds. The initial juiciness and sustained juiciness of meat from Merinos were rated significantly lower by sensory analysis. Meat from Dohne Merino was rated significantly more tender for the attribute first bite. It was demonstrated that Dormer and SAMM sheep had heavier but fatter carcasses than Merinos and Dohne Merinos, with differences in meat quality between breeds.

Autologous peripheral blood progenitor cell (PBPC) transplantation frequently requires sequential placement and use of two separate central venous catheters: (1) a short-term, large-bore, stiff device inserted for leukapheresis, and after removal of that device, (2) a long-term, multi-lumen, flexible, Silastic catheter for administration of high-dose chemotherapy, re-infusion of hematopoietic cells, and intensive supportive care. We reviewed our recent experience with two dual-lumen, large-bore, Silastic multi-purpose ('hybrid') catheters, each of which can be used as a single device for both leukapheresis and long-term supportive care throughout the transplant process. Quinton-Raaf PermCath and Bard-Hickman hemodialysis/apheresis dual-lumen catheters were used as the sole venous access device in 112 consecutive patients who underwent autologous PBPC collection and transplantation. The catheter exit site was monitored three times a week, and lumen patency was assessed using clinical and radiologic techniques. Catheters were removed prematurely for persistent thrombus, positive blood cultures despite appropriate antibiotics, or mechanical dysfunction. There were no intra-operative or immediate post-operative complications relating to insertion. Thirty-two patients experienced catheter occlusion necessitating urokinase instillation. Persistent occlusive problems were noted in 16 patients, and in 10 patients the catheter had to be removed. Two exit site infections and 17 bacteremias occurred. Catheters had to be removed for persistent infection in two subjects and for mechanical problems in five others. Cost analysis comparing the hybrid catheters alone vs conventional devices revealed a charge of $4230 in patients with hybrid catheters vs. $7530 in those requiring a temporary non-Silastic dialysis catheter in addition to a flexible, long-term Silastic catheter. Hybrid, Silastic, dual-lumen, large-bore central venous catheters are safe, cost-effective and convenient

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to perform wide-field imaging, high-resolution spectroscopy, and novel polarization analysis of astrophysical sources. NCT employs a novel Compton telescope design, utilizing 12 high spectral resolution germanium detectors, with the ability to localize photon interaction in three dimensions. NCT underwent its first science flight from Fort Sumner, NM in Spring 2009, and was partially destroyed during a second launch attempt from Alice Spring, Australia in Spring 2010. We will present an overview of the NCT program, including results from the Spring 2009 flight, as well as status and plans for the NCT program.

Stand-off detection is one of the most important radiation detection capabilities for arms control and the control of illicit nuclear materials. For long range passive detection one requires a large detector and a means of “seeing through” the naturally occurring and varying background radiation, i.e. imaging. Arguably, Compton imaging is the best approach over much of the emission band suitable for long range detection. It provides not only imaging, but more information about the direction of incidence of each detected gamma-ray than the alternate approach of coded-aperture imaging. The directional information allows one to reduce the background and hence improve the sensitivity of a measurement. However, to make an efficient Compton imager requires localizing and measuring the simultaneous energy depositions when gamma-rays Compton scatter and are subsequently captured within a single, large detector volume. This concept has been demonstrated in semi-conductor detectors (HPGe, CZT, Si) but at ~ $1k/cm3 these materials are too expensive to build the large systems needed for standoff detection. Scintillator detectors, such as NaI(Tl), are two orders of magnitude less expensive and possess the energy resolution required to make such an imager. However, they do not currently have the ability to localize closely spaced, simultaneous energy depositions in a single large crystal. In this project we are applying a new technique that should, for the first time ever, allow cubic-millimeter event localization in a bulk scintillator crystal.

Excess greenhouse gas emissions and the concomitant effect on global warming have become significant environmental, social and economic threats. In this context, the development of renewable, carbon-neutral and economically feasible biofuels is a driving force for innovation worldwide. A lot of effort has been put into developing biodiesel from microalgae. However, there are still a number of technological, market and policy barriers that are serious obstacles to the economic feasibility and competitiveness of such biofuels. Conversely, there are also a number of business opportunities if the production of such alternative biofuel becomes part of a larger integrated system following the Biorefinery strategy. In this case, other biofuels and chemical products of high added value are produced, contributing to an overall enhancement of the economic viability of the whole integrated system. Additionally, dualpurpose microalgae-bacteria-based systems for treating wastewater and production of biofuels and chemical products significantly contribute to a substantial saving in the overall cost of microalgae biomass production. These types of systems could help to improve the competitiveness of biodiesel production from microalgae, according to some recent Life Cycle Analysis studies. Furthermore, they do not compete for fresh water resources for agricultural purposes and add value to treating the wastewater itself. This work reviews the most recent and relevant information about these types of dualpurpose systems. Several aspects related to the treatment of municipal and animal wastewater with simultaneous recovery of microalgae with potential for biodiesel production are discussed. The use of pre-treated waste or anaerobic effluents from digested waste as nutrient additives for weak wastewater is reviewed. Isolation and screening of microalgae/cyanobacteria or their consortia from various wastewater streams, and studies related to population dynamics in mixed cultures

The Arthur Holly Compton Gamma Ray Observatory (Compton) was launched by the Space Shuttle Atlantis on 5 April 1991. The spacecraft and instruments are in good health and returning exciting results. The mission provides nearly six orders of magnitude in spectral coverage, from 30 keV to 30 GeV, with sensitivity over the entire range an order of magnitude better than that of previous observations. The 16,000 kilogram observatory contains four instruments on a stabilized platform. The mission began normal operations on 16 May 1991 and is now over half-way through a full-sky survey. The mission duration is expected to be from six to ten years. A Science Support Center has been established at Goddard Space Flight Center for the purpose of supporting a vigorous Guest Investigator Program. New scientific results to date include: (1) the establishment of the isotropy, combined with spatial inhomogeneity, of the distribution of gamma-ray bursts in the sky; (2) the discovery of intense high energy (100 MeV) gamma-ray emission from 3C 279 and other quasars and BL Lac objects, making these the most distant and luminous gamma-ray sources ever detected; (3) one of the first images of a gamma-ray burst; (4) the observation of intense nuclear and position-annihilation gamma-ray lines and neutrons from several large solar flares; and (5) the detection of a third gamma-ray pulsar, plus several other transient and pulsing hard X-ray sources.

Dualpurpose systems that treat wastewater and produce lipid rich microalgae biomass have been indicated as an option with great potential for production of biodiesel at a competitive cost. The aim of the present work was to develop a dualpurpose system for the treatment of the anaerobic effluents from pig waste utilizing Neochloris oleoabundans and to evaluate its growth, lipid content and lipid profile of the harvested biomass and the removal of nutrients from the media. Cultures of N. oleoabundans were established in 4 L flat plate photobioreactors using diluted effluents from two different types of anaerobic filters, one packed with ceramic material (D1) and another one packed with volcanic gravel (D2). Maximum biomass concentration in D1 was 0.63 g L(-1) which was significantly higher than the one found in D2 (0.55 g L(-1)). Cultures were very efficient at nutrient removal: 98% for NNH4(+) and 98% for PO4(3-). Regarding total lipid content, diluted eflluents from D2 promoted a biomass containing 27.4% (dry weight) and D1 a biomass containing 22.4% (dry weight). Maximum lipid productivity was also higher in D2 compared to D1 (6.27±0.62 mg L(-1) d(-1) vs. 5.12±0.12 mg L(-1) d(-1)). Concerning the FAMEs profile in diluted effluents, the most abundant one was C18:1, followed by C18:2 and C16:0. The profile in D2 contained less C18:3 (linolenic acid) than the one in D1 (4.37% vs. 5.55%). In conclusion, this is the first report demonstrating that cultures of N. oleoabundans treating anaerobic effluents from pig waste are very efficient at nutrient removal and a biomass rich in lipids can be recovered. The maximum total lipid content and the most convenient FAMEs profile were obtained using effluents from a digester packed with volcanic gravel.

The aim of this study was to determine the socioeconomic, production characteristics and milk production cost of dual-purpose farms (DPF) oriented to milk production in a subtropical region of Central Mexico. The study focused on ten DPF that produce milk all year round, to gather socioeconomic characteristics of farmers (age, family structure, education level), farm resources (land holding, herd structure, infrastructure, management) and economic information during the year 2008. Family labour (FL) covers 66% of labour needs. The average milk production cost was US$0.21, fluctuating from US$0.19 to US$0.31 during the rainy and dry season, respectively. Supplements and hired labour (HL) accounted for 48 and 35% of milk production cost, respectively. Milk production generated daily incomes that covered daily operation costs of farms, as well as the economic needs of the farming family. Calves represented important incomes that ranged between 30 and 50% of total annual farm incomes, cashed in once or twice a year. Milk production provides economic stability to DPF, whereas FL and low input use are key elements that allow low costs in the production of milk and calves in DPF in Central Mexico.

The decreasing supply voltages of digital electronic and high speed ADC (Analog to Digital Converter) and DAC (Digital to Analog Converter) require flexible and high current secondary power distribution system. In the frame of the Inmarsat I-XL program, a 12 kW geomobile SatCom satellite, with 100 V regulated power bus, a multi purposedual output converter was developed for the payload processor as a building block. After a short introduction on the main performance requirements, the baseline architecture is presented. The main drivers of the architecture are reliability, adjustability, radiation tolerant and single event free, volume and mass. The combination of all these constraints highlights the need of significant breakthrough in various domains. Many research results related to packaging and power electronic topics are brought up. These results directly drive the adopted solution presented in the next step followed by a description of the integration of the defined building block in the Inmarsat I-XL payload IP (Integrated Processor). Finally, the main electrical performances such as output ripple and spikes, load step transient and stability are summarized.

Clearwater Russet is a russet-skinned potato cultivar suitable for processing or fresh pack. It is notable for having a low incidence of external defects that contributes to its high U.S. No 1 yield relative to the dual-purpose industry standard, Russet Burbank. Clearwater Russet also has exceptio...

Interseeded alfalfa could serve as a dualpurpose crop for providing groundcover during silage corn production and forage during subsequent years of production, but this system has been unworkable because competition between the co-planted crops often leads to stand failure of interseeded alfalfa an...

Genetic and phenotypic parameters were estimated for production and disease traits (including dagginess) from about 2 million pedigree-recorded animals born between 1990 and 2008 in New Zealand dual-purpose ram breeding flocks. This is the most comprehensive study of genetic parameter estimates for the New Zealand sheep industry to date and includes estimates that have not previously been reported. Estimates of heritability were moderate for BW at 8 mo (LW8), fleece weight at 12 mo (FW12), dagginess score at 3 and 8 mo (DAG3, DAG8; 0.31 to 0.37), typical for weaning weight (WWT), fecal egg count in summer (FEC1) and autumn (FEC2), and analogous Nematodirus counts (NEM1, NEM2; 0.17 to 0.21), and low for number of lambs born to ewes (NLB; 0.09). The genetic correlations among production traits, WWT, LW8, and FW12, were positive and moderate to high. Correlations of DAG3 and DAG8 with production and disease traits were low and mostly negative. The NLB had low, but typically positive, correlations with other traits. Disease traits also had low, but positive, correlations with production traits (WWT, LW8, and FW12), and were highly correlated among themselves. In general, the heritability estimate for BW and dagginess were greater than what is currently used in the New Zealand genetic evaluation service (Sheep Improvement Limited), and the availability of accurate estimates for dagginess plus parasite resistance and their genetic correlations with production traits will enable more accurate breeding values to be estimated for New Zealand sheep.

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

Analysis of perfusion-based bioreactors for organ engineering and a detailed evaluation of physical and biochemical parameters that measure dynamic changes within maturing cell-laden scaffolds are critical components of ex vivo tissue development that remain understudied topics in the tissue and organ engineering literature. Intricately designed bioreactors that house developing tissue are critical to properly recapitulate the in vivo environment, deliver nutrients within perfused media, and monitor physiological parameters of tissue development. Herein, we provide an in-depth description and analysis of two dual-purpose perfusion bioreactors that improve upon current bioreactor designs and enable comparative analyses of ex vivo scaffold recellularization strategies and cell growth performance during long-term maintenance culture of engineered kidney or liver tissues. Both bioreactors are effective at maximizing cell seeding of small-animal organ scaffolds and maintaining cell survival in extended culture. We further demonstrate noninvasive monitoring capabilities for tracking dynamic changes within scaffolds as the native cellular component is removed during decellularization and model human cells are introduced into the scaffold during recellularization and proliferate in maintenance culture. We found that hydrodynamic pressure drop (ΔP) across the retained scaffold vasculature is a noninvasive measurement of scaffold integrity. We further show that ΔP, and thus resistance to fluid flow through the scaffold, decreases with cell loss during decellularization and correspondingly increases to near normal values for whole organs following recellularization of the kidney or liver scaffolds. Perfused media may be further sampled in real time to measure soluble biomarkers (e.g., resazurin, albumin, or kidney injury molecule-1) that indicate degree of cellular metabolic activity, synthetic function, or engraftment into the scaffold. Cell growth within bioreactors is

Analysis of perfusion-based bioreactors for organ engineering and a detailed evaluation of physical and biochemical parameters that measure dynamic changes within maturing cell-laden scaffolds are critical components of ex vivo tissue development that remain understudied topics in the tissue and organ engineering literature. Intricately designed bioreactors that house developing tissue are critical to properly recapitulate the in vivo environment, deliver nutrients within perfused media, and monitor physiological parameters of tissue development. Herein, we provide an in-depth description and analysis of two dual-purpose perfusion bioreactors that improve upon current bioreactor designs and enable comparative analyses of ex vivo scaffold recellularization strategies and cell growth performance during long-term maintenance culture of engineered kidney or liver tissues. Both bioreactors are effective at maximizing cell seeding of small-animal organ scaffolds and maintaining cell survival in extended culture. We further demonstrate noninvasive monitoring capabilities for tracking dynamic changes within scaffolds as the native cellular component is removed during decellularization and model human cells are introduced into the scaffold during recellularization and proliferate in maintenance culture. We found that hydrodynamic pressure drop (ΔP) across the retained scaffold vasculature is a noninvasive measurement of scaffold integrity. We further show that ΔP, and thus resistance to fluid flow through the scaffold, decreases with cell loss during decellularization and correspondingly increases to near normal values for whole organs following recellularization of the kidney or liver scaffolds. Perfused media may be further sampled in real time to measure soluble biomarkers (e.g., resazurin, albumin, or kidney injury molecule-1) that indicate degree of cellular metabolic activity, synthetic function, or engraftment into the scaffold. Cell growth within bioreactors is

Dual-purpose casks can be utilized for dry interim storage and transportation of the highly radioactive spent fuel assemblies (SFAs) of Bushehr Nuclear Power Plant (NPP). Criticality safety analysis was carried out using the MCNP code for the cask containing 12, 18, or 19 SFAs. The basket materials of borated stainless steel and Boral (Al-B4C) were investigated, and the minimum required receptacle pitch of the basket was determined.

It is hypothesized that the combined effects of suckling and milking in the dualpurpose cows is one of the main suppressors of reproductive efficiency in this production system. The experiment described here examined whether managing the interval between milking and suckling could reduce the postpartum anoestrous period and whether the presence of a teaser bull could enhance the effects of these managements. The experiment involved 39 Bos taurus x Bos indicus cows which had an average weight of 523.0 +/- 12.8 kg (mean +/- S.E.M.) and body condition score of 5-7 (scale 1-9) at calving. The cows and calves grazed separate pastures and the cows were supplemented with 2 kg 17% CP concentrates and 1 kg molasses per cow per day. The experiment was conducted over the first 100 days postpartum. Cows were hand-milked once per day in the presence of the calf to stimulate milk release. The factors in the 2 x 2 design were the milking to suckling interval (0 h, control suckling; CS versus 8 h prolonged-delay suckling; PDS) and no exposure versus exposure to a teaser bull (B). Cows were assigned at random within calving date to the four treatments: CS (n = 10), PDS (n = 10), CS-B (n = 9) and PDS-B (n = 10). Cows on treatments CS and CS-B had three-quarters of the udder milked and one-quarter was not milked. The entire udder was milked on those treatments where there was an interval between milking and suckling. The bull was introduced 7 days after calving in treatments where the cows were exposed to a teaser bull. Body weights of cows and calves and cow milk yield were recorded. Weekly blood samples were collected for plasma progesterone assay. Data were analyzed by ANOVA in a 2 x 2 factorial design and by chi(2)-test. There were no statistically significant differences between treatments in cow body weight at calving and at 100 days postpartum, nor in milk yield (overall mean 6.0 +/- 1.1 kg per day). Calf daily gain was 598 +/- 25 g for treatments CS and CS-B in which

Characterization of GRETINA as a polarimeter using the tracking technique has been done by examing the gamma-rays emitted from polarized states following the 24Mg(p,p') reaction. Here we consider GRETINA as a traditional Compton polarimeter, where the intensity of the scattered radiation measured between physical detecting elements is used to determine its polarization sensitivity using techniques developed over the past decades. This provides a direct basic measure of the linear polarization of the array independent of the signal-decomposition and tracking algorithms, and directly comparable to traditional Compton polarimeters. The performance of GRETINA as a traditional Compton-polarimeter will be presented. This material is based upon work supported by the U.S. Department of Energy, Office of Science and Office of Nuclear Physics under Contracts Number DE-AC02-05CH11231(LBNL) and Number DE-AC02-06CH11357(ANL).

Generation of high-energy photons via collision of relativistic electron and laser beams is known as inverse Compton scattering or laser Compton scattering. Compton sources, photon sources based on Compton scattering, have been developed in the world to realize high-flux/high-brightness X-ray/gamma-ray sources and exploit applications with energy-tunable and narrow-bandwidth photon beams from these sources. Recent progress of electron accelerator and laser technologies will open a new era in Compton sources. An electron beam of small emittance and high-average current contributes to improving spectral brightness of Compton scattered photons. Flux of generating photons is also increased by a high-power laser together with apparatus such as laser enhancement cavity. We overview the current status of Compton sources including an experiment carried out at the Compact ERL, which is the first demonstration of Compton scattering by combination of an energy-recovery linac and a laser enhancement cavity.

It is demonstrated, that with exclusive final state, data from electron scattering experiments that are recorded with loose trigger requirements can be used to analyze photoproduction reactions. A preliminary results on Timelike Compton Scattering using the electroproduction data from the CLAS detector at Jefferson Lab are presented. In particular, using final state (pe{sup -}e{sup +}) photoproduction of vector mesons and timelike photon is studied. Angular asymmetries in Timelike Compton Scattering region is compared with model predictions in the framework of Generalized Parton Distribution.

At Lawrence Livermore National Laboratory, we are pursuing the development of a gamma-ray imaging system using the Compton effect. We have built our first generation hybrid Compton imaging system, and we have conducted initial calibration and image measurements using this system. In this paper, we present the details of the hybrid Compton imaging system and initial calibration and image measurements.

Free terpenoids and both free and bound polyfunctional thiols were investigated in five selected dual-purpose hop cultivars. Surprisingly, the dual-purpose Sorachi Ace variety was found to contain higher amounts of farnesene (2101 mg/kg) than aromatic hops such as Saaz but only traces of 3-methylbutylisobutyrate, a compound that usually distinguishes all bitter varieties. All five cultivars investigated here showed an exceptional citrus-like potential explained by either monoterpenic alcohols or polyfunctional thiols. Among the monoterpenic alcohols, β-citronellol at concentrations above 7 mg/kg distinguished Amarillo, Citra, Hallertau Blanc, Mosaic, and Sorachi Ace from Nelson Sauvin and Tomahawk, two previously investigated dual-purpose hops, while linalool (312 mg/kg) and geraniol (211 mg/kg) remained good discriminating compounds for Nelson Sauvin and Tomahawk, respectively. Regarding polyfunctional thiols, higher amounts of 3-sulfanylhexyl acetate (27 μg/kg) characterized the Citra variety. Free 4-sulfanyl-4-methylpentan-2-one proved discriminant for Sorachi Ace, while the bound form is predominant in Nelson Sauvin. On the other hand, an S-conjugate of 3-sulfanylhexan-1-ol was found in Sorachi Ace at levels not far from those previously reported for Cascade, although the free form was undetected here. Both free and bound grapefruit-like 3-sulfanyl-4-methylpentan-1-ol (never evidenced before the present work) emerged as discriminating compounds for the Hallertau Blanc variety. The apotryptophanase assay also allowed us to evidence for the first time an S-conjugate of 2-sulfanylethan-1-ol.

The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

A cross-sectional study was carried out to determine the seroprevalence and risk factors associated with bovine respiratory syncytial virus (BRSV) infection in non-vaccinated dairy and dual-purpose cattle herds from Ecuador. A total of 2,367 serum samples from 346 herds were collected from June 2008 to February 2009. A questionnaire, which included variables related to cattle, health, management measures, and the environment, was filled out in each herd. Presence of antibodies against BRSV was analyzed using a commercial indirect ELISA test. A logistic regression model was used to determine risk factors associated with BRSV at herd level. The individual seroprevalence against BRSV in non-vaccinated herds in Ecuador was 80.48% [1,905/2,367; 95% confidence interval (CI) = 78.9-82.1]. The herd prevalence was 91.3% (316/346; 95% CI = 88.3-94.3), and the intra-herd prevalence ranged between 25% and 100% (mean, 90.47%). The logistic regression model showed that the existence of bordering cattle farms, the dual-purpose farms, and the altitude of the farm (more than 2,338 m above sea level) were risk factors associated with BRSV infection. This is the first study about BRSV prevalence in Ecuador. It shows the wide spread of the BRSV infection in the country. The risk factors found will help to design effective control strategies.

This study was designed to analyze the low input backyard poultry production system practiced by the tribal farmers, and evaluate the performance of an improved dual-purpose breed, the Vanaraja. Results revealed that a significantly (p < 0.05) higher number of farmers used temporary, non-conventional poultry houses made of locally available materials, such as bamboo and wood. Most of the farmers (65.9 %) did not provide balanced feed to their poultry and did not vaccinate their birds against any disease. Under standard management conditions, the average body weight of Vanaraja birds at 6 weeks was 625 +/- 10.9 g. Under backyard conditions, the body weight at 18 months was 3.6 +/- 0.8 kg. The age at first egg was 154 +/- 9 days in the backyard system, whereas under the intensive system it was 196 +/- 4 days. Annual production under the backyard and intensive systems of rearing was 176 +/- 9 and 152 +/- 7 eggs, respectively. Mortality of adult birds was 12 % and predation by foxes and wild cats accounted for 1.67 %. This study revealed that village chickens are an important income source for household expenses, and that traditional free-range poultry production in the smallholder sector of developing countries can possibly be improved through the use of improved dual-purpose birds.

Calibration techniques for a medium energy gamma ray telescope are described. Gain calibration using Compton edge spectra involves comparisons of pulse height spectra with spectra simulated by a Monte Carlo computer code which includes Compton scattering and pair production, plural scattering and variable energy resolution, and cell size. The telescope considered comprises 56 cells of liquid scintillator in four size groups, with a total liquid volume of 325 l; each cell has its own photomultiplier tube. Energy and angular resolutions and the PMT gain calibration procedure are verified with double scatter data for monoenergetic gamma rays at a known location. Detection probabilities for any cell combination in the two telescope arrays are calculated per steradian as a function of the scattering for a number of different energies with a Van de Graaff accelerator.

The SPEctroscopic Imager for {gamma}-Rays (SPEIR) is a new concept of a compact {gamma}-ray imaging system of high efficiency and spectroscopic resolution with a 4-{pi} field-of-view. The system behind this concept employs double-sided segmented planar Ge detectors accompanied by the use of list-mode photon reconstruction methods to create a sensitive, compact Compton scatter camera.

Dual x-ray absorptiometry is widely used in analyzing body composition and imaging. We discuss the physics of the method and exhibit its limitations and show it is related to the Compton and photoelectric contributions to the x-ray absorption coefficients of materials.

The Compton-Dry Cask Imaging Scanner is a system that verifies and documents the presence of spent nuclear fuel rods in dry-cask storage and determines their isotopic composition without moving or opening the cask. For more information about this project, visit http://www.inl.gov/rd100/2011/compton-dry-cask-imaging-system/

The Compton-Dry Cask Imaging Scanner is a system that verifies and documents the presence of spent nuclear fuel rods in dry-cask storage and determines their isotopic composition without moving or opening the cask. For more information about this project, visit http://www.inl.gov/rd100/2011/compton-dry-cask-imaging-system/

Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro-channel plate) to provide gating and high DQE at the 40-200 keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Experiments were performed at energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.

Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro-channel plate) to provide gating and high DQE at the 40-200 keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Experiments were performed at energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.

The All-Sky Compton Imager (ASCI) is a mission concept for MeV Gamma-Ray astronomy. It consists of a compact array of cross-strip germanium detectors, shielded only by a plastic anticoicidence, and weighting less than 100 kg. Situated on a deployable structure at a distance of 10 m from the spacecraft orbiting at L2 or in a HEO, the ASCI not only avoids albedo- and spacecraft-induced background, but it benefits from a continuous all-sky exposure. The modest effective area is more than compensated by the 4 π field-of-view. Despite its small size, ASCI's γ-ray line sensitivity after its nominal lifetime of 3 years is ~ 10-6 ph cm-2 s-1 at 1 MeV for every γ-ray source in the sky. With its high spectral and 3-D spatial resolution, the ASCI will perform sensitive γray spectroscopy and polarimetry in the energy band 100 keV-10 MeV. The All-Sky Compton Imager is particularly well suited to the task of measuring the Cosmic Gamma-Ray Background - and simultaneously covering the wide range of science topics in gamma-ray astronomy.

The application of synchro-Compton theory to real compact radio sources, the question of a self-Compton origin of the X-rays in radio-loud quasars and active galactic nuclei, and the phenomenology of superluminal motion are discussed in a review of research concerning synchro-Compton emission from superluminal sources. After examining the basic synchro-Compton theory of ideal sources, applications of the theory to real sources is discussed. It is concluded that the Compton problem and total energy requirements are not substantially mitigated by considering source structures more complicated than the multiple, uniform-component model used by most investigators. Also, alternatives to the standard model of superluminal motion are discussed, focusing on the assumptions usually made when interpreting superluminal sources.

This study aimed at estimating the relationships between linear type traits and milk production in the dual-purpose Aosta Red Pied (ARP) cattle breed, by expressing type traits as factor scores with the same biological meaning of the individual traits. Factor analysis was applied to individual type traits for muscularity and udder of 32,275 first-parity ARP cows, obtaining 3 factor scores for individual muscularity (F1), udder side (F2), and udder conformation (F3). Data from 169,008 test-day records of milk, fat, and protein yield (kg), belonging to the first 3 lactations of 16,605 cows, were also analyzed. After obtaining genetic parameters for both morphological factors and milk production traits through a series of AIREML single-trait models, bivariate analyses were performed on a data set accounting for 201,283 records of 35,530 cows, to assess the phenotypic and genetic correlations among all factor scores and milk yield traits. The heritability estimates obtained proved to be moderate for both groups of traits, ranging from 0.132 (fat) to 0.314 (F1). Muscularity factor showed moderate and negative genetic correlations (ra) with udder size (-0.376) and udder conformation (0.214) factors. A low and negative ra was found between udder factors. Strong and positive ra were found among all the 3 milk production traits and F 0010 (ra≥0.597). Negative ra with milk traits were obtained for both F 0005 and F3, ranging from -0.417 to -0.221. Phenotypic correlations were lower than the genetic ones, and sometimes close to zero. The antagonism between milk production and meat attitude traits suggests that great attention should be paid in assigning proper weight to the traits, comprising functional traits such as udder conformation, included in selection indices for the dual-purpose breed. The ra obtained for factor scores are consistent with previous estimates for the corresponding individual type traits, and this confirms the possible use of factor analysis to

Radiation pressure dominated accretion discs around compact objects may have turbulent velocities that greatly exceed the electron thermal velocities within the disc. Bulk Comptonization by the turbulence may therefore dominate over thermal Comptonization in determining the emergent spectrum. Bulk Comptonization by divergenceless turbulence is due to radiation viscous dissipation only. It can be treated as thermal Comptonization by solving the Kompaneets equation with an equivalent `wave' temperature, which is a weighted sum over the power present at each scale in the turbulent cascade. Bulk Comptonization by turbulence with non-zero divergence is due to both pressure work and radiation viscous dissipation. Pressure work has negligible effect on photon spectra in the limit of optically thin turbulence, and in this limit radiation viscous dissipation alone can be treated as thermal Comptonization with a temperature equivalent to the full turbulent power. In the limit of extremely optically thick turbulence, radiation viscous dissipation is suppressed, and the evolution of local photon spectra can be understood in terms of compression and expansion of the strongly coupled photon and gas fluids. We discuss the consequences of these effects for self-consistently resolving and interpreting turbulent Comptonization in spectral calculations in radiation magnetohydrodynamic simulations of high luminosity accretion flows.

A cross-sectional study was carried out, from November 2007 to March 2008, to estimate the prevalence of and to determine risk factors associated with bovine syncytial respiratory virus (BRSV) and parainfluenza 3 virus (PIV3) in dual-purpose herds in Colima, México. One hundred and seventy-six sera from 33 herds for PIV3 and 232 sera from 44 herds for BRSV were used. Sera were analyzed by indirect ELISA for the detection of antibodies against BRSV and PIV3 in cattle herds to determine the seroprevalence of respiratory diseases. The apparent and true prevalences for PIV3 were 60.8% and 54.4% and for BRSV 52.2% and 50.8%, respectively. The percentage of herds showing at least one positive animal was 78.7% for PIV3, and 93.2% for BRSV. Age (≤ 12, 13-48, and >48 months old) and respiratory signs (no, yes) showed significant association (P < 0.05) with PIV3 and age with BRSV. This study showed that animals were exposed to both viruses and that age was the main risk factor. The need to establish new vaccination plans to effectively protect cattle against those infections in the state of Colima, Mexico is suggested.

The age-dependent production kinetics of ginsenosides and an anthocyanin pigment in a cell suspension line of Panax sikkimensis was followed in vitro. Highest total saponin content [7.37 mg/g dry weight (DW)] and biomass accumulation (% biomass increase = 209.67) in this line occurred after 3 and 5 weeks of culture, respectively. Accumulation of individual protopanaxatriol (Re, Rg1, and Rg2) and protopanaxadiol (Rb1, Rb2, and Rc) ginsenosides showed a variable pattern of accumulation independent of cell biomass buildup during the 7-week culture cycle. However, total content of triol ginsenosides was always significantly more than the diol group of ginsenosides, being 183.2-, 63.5-, and 72.1-folds at third, fourth, and fifth week stage of cell growth. Interestingly, in addition to these ginsenosides, the cell line also co-accumulated an anthocyanin pigment in vitro. The pigment content increased gradually from 8.66 to 14.29 mg/g DW after first to fifth week followed by a marginal fall to 12.79 and 10.95 mg/g DW during next 2 weeks. Therefore, in terms of total recovery of saponins (77.4 mg/l) and anthocyanin (199.16 mg/l), harvesting of cells after 3 and 5 weeks of growth was most profitable, respectively. The possible utility of this dualpurpose cell line in nutraceutical industry is discussed.

This photograph shows the Compton Gamma-Ray Observatory being released from the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-35 mission in April 1991. The GRO reentered the Earth's atmosphere and ended its successful mission in June 2000. For nearly 9 years, GRO's Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center, kept an unblinking watch on the universe to alert scientist to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of star, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in BATSE's science program.

This photograph shows the Compton Gamma-Ray Observatory (GRO) being deployed by the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-37 mission in April 1991. The GRO reentered Earth atmosphere and ended its successful mission in June 2000. For nearly 9 years, the GRO Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center (MSFC), kept an unblinking watch on the universe to alert scientists to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of stars, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in the BATSE science program.

The IBIS instrument launched on board the ESA INTEGRAL observatory on October 2002 is a coded mask telescope composed by two position sensitive detection planes, one with 16384 Cadmium Telluride pixels (ISGRI) and the other with 4096 Caesium Iodide pixels (PICsIT). Events detected in coincidence in the two detector layers are flagged as generated by Compton scattered photons and can be then processed and filtered using the Compton kinematic equations. The analysis of these data is, however, quite complex, mainly due to the presence of a great number of fake events generated by random coincidences between uncorrelated ISGRI and PICsIT events; if this component is not subtracted with great accuracy, false source detections can be produced. In this work, we present the performance (spectral and imaging) obtainable from the IBIS Compton data, by analyzing ground calibration acquisitions. We also analyze the IBIS Compton flight data relative to the Crab observation, to determine its scientific capabilities.

Black hole and neutron star accretion flows display unusually high levels of hard coronal emission in comparison to all other optically thick, gravitationally bound, turbulent astrophysical systems. Since these flows sit in deep relativistic gravitational potentials, their random bulk motions approach the speed of light, therefore allowing turbulent Comptonization to be an important effect. We show that the inevitable production of hard X-ray photons results from turbulent Comptonization in the limit where the turbulence is trans-sonic and the accretion power approaches the Eddington limit. In this regime, the turbulent Compton y-parameter approaches unity and the turbulent Compton temperature is a significant fraction of the electron rest mass energy, in agreement with the observed phenomena.

With the aim of developing the application of neutron Compton scattering (NCS) to molecular systems of biophysical interest, we are using the Compton spectrometer EVS at ISIS to characterize the momentum distribution of protons in peptide groups. In this contribution we present NCS measurements of the recoil peak (Compton profile) due to the amide proton in otherwise fully deuterated acetanilide (ACN), a widely studied model system for H-bonding and energy transfer in biomolecules. We obtain values for the average width of the potential well of the amide proton and its mean kinetic energy. Deviations from the Gaussian form of the Compton profile, analyzed on the basis of an expansion due to Sears, provide data relating to the Laplacian of the proton potential.

The profitability of dual-purpose breeding farms can be increased through genetic improvement of carcass traits. To develop a genetic evaluation of carcass traits of young bulls, breed-specific genetic parameters were estimated in three French dual-purpose breeds. Genetic correlations between these traits and veal calf, type and milk production traits were also estimated. Slaughter performances of 156 226 Montbeliarde, 160 361 Normande and 8691 Simmental young bulls were analyzed with a multitrait animal model. In the three breeds, heritabilities were moderate for carcass weight (0.12 to 0.19±0.01 to 0.04) and carcass conformation (0.21 to 0.26±0.01 to 0.04) and slightly lower for age at slaughter (0.08 to 0.17±0.01 to 0.03). For all three breeds, genetic correlations between carcass weight and carcass conformation were moderate and favorable (0.30 to 0.52±0.03 to 0.13). They were strong and favorable (-0.49 to -0.71±0.05 to 0.15) between carcass weight and age at slaughter. Between age at slaughter and carcass conformation, they were low and unfavorable to moderate and favorable (-0.25 to 0.10±0.06 to 0.18). Heavier young bulls tend to be better conformed and slaughtered earlier. Genetic correlations between corresponding young bulls and veal production traits were moderate and favorable (0.32 to 0.70±0.03 to 0.09), implying that selecting sires for veal calf production leads to select sires producing better young bulls. Genetic correlations between young bull carcass weight and cow size were moderately favorable (0.22 to 0.45±0.04 to 0.10). Young bull carcass conformation had moderate and favorable genetic correlations (0.11 to 0.24±0.04 to 0.10) with cow width but moderate and unfavorable genetic correlations (-0.21 to -0.36±0.03 to 0.08) with cow height. Taller cows tended to produce heavier young bulls and thinner cows to produce less conformed ones. Genetic correlations between carcass traits of young bulls and cow muscularity traits were low to

A cross-sectional study was carried out to determine the seroprevalence and risk factors associated to Bovine Herpesvirus 1 (BHV-1) infection in non-vaccinated dairy and dualpurpose cattle herds from Ecuador. A total of 2367 serum samples from 346 herds were collected from June 2008 through February 2009. A questionnaire, which included variables related to cattle, health, management measures and environment was filled out in each herd. A commercial indirect ELISA test was used to determine the seropositivity against BHV-1. Generalized Estimating Equations (GEE) model was used to determine risk factors at individual level, including herd as random effect. The individual seroprevalence to BHV-1 in Ecuador was 43.2% (1023/2367; CI(₉₅%): 41.2-45.2%). The herd prevalence was 82.1%; (284/346; CI(₉₅%): 78.1-86.1%) and the intra-herd prevalence ranged from 12.5 to 100% (mean=64.1%). The GEE model showed that animal age (>4 years) (OR: 1.44; CI(₉₅%): 1.18-1.75), BRSV infection (OR: 1.45; CI(₉₅%): 1.09-1.92), altitude over the sea level (≤ 1800 m) (OR: 2.97; CI(₉₅%): 2.1-4.22) and average slope (> 11%) (OR: 1.45; CI(₉₅%): 1.07-1.95) are risk factors associated with BHV-1 infection, while a good cleaning of the facilities (OR: 0.66; CI(₉₅%): 0.44-0.99) was shown to be a protective factor.

The most serious terrorist threat we face today may come from radiological dispersion devices and unsecured nuclear weapons. It is imperative for national security that we develop and implement radiation detection technology capable of locating and tracking nuclear material moving across and within our borders. Many radionuclides emit gamma rays in the 0.2-3 MeV range. Unfortunately, current gamma ray detection technology is inadequate for providing precise and efficient measurements of localized radioactive sources. Common detectors available today suffer from large background rates and have only minimal ability to localize the position of the source without the use of mechanical collimators, which reduces efficiency. Imaging detectors using the Compton scattering process have the potential to provide greatly improved sensitivity through their ability to reject off-source background. We are developing a prototype device to demonstrate the Compton imaging technology. The detector consists of several layers of pixelated silicon detectors followed by an array of CsI crystals coupled to photodiodes. Here we present the concept of our detector design and results from Monte Carlo simulations of our prototype detector. Development of technologies for detecting and characterizing radiation from various nuclear materials is important for many fields, including homeland security, astrophysics, and medical imaging. Unfortunately, in many cases we now largely use detection technologies that were developed in the 1960s. While sufficient for some purposes, these technologies have proved inadequate for remote sensing of radioactive nuclear materials - a crucial capability required for enhanced homeland security. Passive gamma ray detection is the most direct means of providing this capability, but current detectors are severely limited in sensitivity and detection range due to confusion from off-source backgrounds, and they cannot precisely localize sources when they are

The objective of this work is to investigate Compton camera technology for spectroscopic imaging of gamma rays in the 100keV to 1MeV range. An efficient, specific purpose Monte Carlo code was developed to investigate the image formation process in Compton cameras. The code is based on a pathway sampling technique with extensive use of variance reduction techniques. The code includes detailed Compton scattering physics, including incoherent scattering functions, Doppler broadening, and multiple scattering. Experiments were performed with two different camera configurations for a scene containing a 75Se source and a 137Cs source. The first camera was based on a fixed silicon detector in the front plane and a CdZnTe detector mounted in the stage. The second camera configuration was based on two CdZnTe detectors. Both systems were able to reconstruct images of 75Se, using the 265keV line, and 137Cs, using the 662keV line. Only the silicon-CdZnTe camera was able to resolve the low intensity 400keV line of 75Se. Neither camera was able to reconstruct the 75Se source location using the 136keV line. The energy resolution of the silicon-CdZnTe camera system was 4% at 662keV. This camera reproduced the location of the 137Cs source by event circle image reconstruction with angular resolutions of 10° for a source on the camera axis and 14° for a source 30° off axis. Typical detector pair efficiencies were measured as 3 x 10-11 at 662keV. The dual CdZnTe camera had an energy resolution of 3.2% at 662keV. This camera reproduced the location of the 137Cs source by event circle image reconstruction with angular resolutions of 8° for a source on the camera axis and 12° for a source 20° off axis. Typical detector pair efficiencies were measured as 7 x 10-11 at 662keV. Of the two prototype camera configurations tested, the silicon-CdZnTe configuration had superior imaging characteristics. This configuration is less sensitive to effects caused by source decay cascades and random

The Voxel Imaging PET (VIP) project presents a new approach for the design of nuclear medicine imaging devices by using highly segmented pixel CdTe sensors. CdTe detectors can achieve an energy resolution of ≈ 1% FWHM at 511 keV and can be easily segmented into submillimeter sized voxels for optimal spatial resolution. These features help in rejecting a large part of the scattered events from the PET coincidence sample in order to obtain high quality images. Another contribution to the background are random events, i.e., hits caused by two independent gammas without a common origin. Given that 60% of 511 keV photons undergo Compton scattering in CdTe (i.e. 84% of all coincidence events have at least one Compton scattering gamma), we present a simulation study on the possibility to use the Compton scattering information of at least one of the coincident gammas within the detector to reject random coincidences. The idea uses the fact that if a gamma undergoes Compton scattering in the detector, it will cause two hits in the pixel detectors. The first hit corresponds to the Compton scattering process. The second hit shall correspond to the photoelectric absorption of the remaining energy of the gamma. With the energy deposition of the first hit, one can calculate the Compton scattering angle. By measuring the hit location of the coincident gamma, we can construct the geometric angle, under the assumption that both gammas come from the same origin. Using the difference between the Compton scattering angle and the geometric angle, random events can be rejected.

Purpose: This work is to evaluate the effects of Compton current generation in three small-volume ionization chambers on measured beam characteristics for electron fields. Methods: Beam scans were performed using Exradin A16, A26, and PTW 31014 microchambers. Scans with varying chamber components shielded were performed. Static point measurements, output factors, and cable only irradiations were performed to determine the contribution of Compton currents to various components of the chamber. Monte Carlo simulations were performed to evaluate why one microchamber showed a significant reduction in Compton current generation. Results: Beam profiles demonstrated significant distortion for two of the three chambers when scanned parallel to the chamber axis, produced by electron deposition within the wire. Measurements of ionization produced within the cable identified Compton current generation as the cause of these distortions. The size of the central collecting wire was found to have the greatest influence on the magnitude of Compton current generation. Conclusions: Microchambers can demonstrate significant (>5%) deviations from properties as measured with larger volume chambers (0.125 cm{sup 3} and above). These deviations can be substantially reduced by averaging measurements conducted at opposite polarities.

In this work, we investigate the use of a three-stage Compton camera to measure secondary prompt gamma rays emitted from patients treated with proton beam radiotherapy. The purpose of this study was (1) to develop an optimal three-stage Compton camera specifically designed to measure prompt gamma rays emitted from tissue and (2) to determine the feasibility of using this optimized Compton camera design to measure and image prompt gamma rays emitted during proton beam irradiation. The three-stage Compton camera was modeled in Geant4 as three high-purity germanium detector stages arranged in parallel-plane geometry. Initially, an isotropic gamma source ranging from 0 to 15 MeV was used to determine lateral width and thickness of the detector stages that provided the optimal detection efficiency. Then, the gamma source was replaced by a proton beam irradiating a tissue phantom to calculate the overall efficiency of the optimized camera for detecting emitted prompt gammas. The overall calculated efficiencies varied from ~10-6 to 10-3 prompt gammas detected per proton incident on the tissue phantom for several variations of the optimal camera design studied. Based on the overall efficiency results, we believe it feasible that a three-stage Compton camera could detect a sufficient number of prompt gammas to allow measurement and imaging of prompt gamma emission during proton radiotherapy.

In this work, we investigate the use of a three-stage Compton camera to measure secondary prompt gamma rays emitted from patients treated with proton beam radiotherapy. The purpose of this study was (1) to develop an optimal three-stage Compton camera specifically designed to measure prompt gamma rays emitted from tissue and (2) to determine the feasibility of using this optimized Compton camera design to measure and image prompt gamma rays emitted during proton beam irradiation. The three-stage Compton camera was modeled in Geant4 as three high-purity germanium detector stages arranged in parallel-plane geometry. Initially, an isotropic gamma source ranging from 0 to 15 MeV was used to determine lateral width and thickness of the detector stages that provided the optimal detection efficiency. Then, the gamma source was replaced by a proton beam irradiating a tissue phantom to calculate the overall efficiency of the optimized camera for detecting emitted prompt gammas. The overall calculated efficiencies varied from ∼ 10(-6) to 10(-3) prompt gammas detected per proton incident on the tissue phantom for several variations of the optimal camera design studied. Based on the overall efficiency results, we believe it feasible that a three-stage Compton camera could detect a sufficient number of prompt gammas to allow measurement and imaging of prompt gamma emission during proton radiotherapy.

Russia, stores large quantities of spent nuclear fuel (SNF) from submarine and ice-breaker nuclear powered naval vessels. This high-level radioactive material presents a significant threat to the Arctic and marine environments. Much of the SNF from decommissioned Russian nuclear submarines is stored either onboard the submarines or in floating storage vessels in Northwest and Far East Russia. Some of the SNF is damaged, stored in an unstable condition, or of a type that cannot currently be reprocessed. In many cases, the existing Russian transport infrastructure and reprocessing facilities cannot meet the requirements for moving and reprocessing all of this fuel from remote locations. Additional transport and storage options are required. Some of the existing storage facilities being used in Russia do not meet health and safety and physical security requirements. The U.S. has assisted Russia in the development of a new dual-purpose metal-concrete transport and storage cask (TUK-108/1) for their military SNF and assisted them in building several new facilities for off-loading submarine SNF and storing these TUK-108/1 casks. These efforts have reduced the technical, ecological, and security challenges for removal, handling, interim storage, and shipment of this submarine fuel. Currently, Russian licensing limits the storage period of the TUK-108/1 casks to no more than two years before the fuel must be shipped for reprocessing. In order to extend this licensed storage period, a system is required to condition the casks by removing residual water and creating an inert storage environment by backfilling the internal canisters with a noble gas such as argon. The U.S. has assisted Russia in the development of a mobile cask conditioning system for the TUK-108/1 cask. This new conditioning system allows the TUK 108/1 casks to be stored for up to five years after which the license may be considered for renewal for an additional five years or the fuel will be shipped to

The Arthur Holly Compton Gamma Ray Observatory (Compton) is the second in NASA's series of Great Observatories. Compton has now been operating for over two and a half years, and has given a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made and continue to be made. The authors describe the capabilities of the four scientific instruments and the observing programs for the first three years of the mission. During Phases 2 and 3 of the mission a Guest Investigator program has been in progress with the Guest Observers' time share increasing from 30% to over 50% for the later mission phases.

A major goal of the 12 GeV upgrade at Jefferson Lab is to map out the Generalized Parton Distributions (GPDs) in the valence region. This is primarily done through Deeply Virtual Compton Scattering (DVCS), which provides the simplest and cleanest way of accessing the GPDs. However, the “inverse” process, Timelike Compton Scattering (TCS), can provide an important complement, in particular formeasuring the real part of the amplitude and understanding corrections at finite Q2. The first measurements of TCS have recently been carried out in Hall B at Jefferson Lab, using both tagged and untagged photon beams.

Quasi-thermal Comptonization in internal shocks formed between relativistic shells can account for the high energy emission of gamma-ray bursts (GRB). This is the dominant cooling mechanism if the typical energy of the emitting particles is achieved either through the balance between heating and cooling or as a result of electron-positron (e(+/-) ) pair production. Both processes yield sub/mildly relativistic energies. In this case the synchrotron spectrum is self-absorbed, providing the seed photons for the Comptonization process, whose spectrum is flat [F(nu ) ~ const], ending either in an exponential cutoff or a Wien peak.

We describe a front-end application specific integrated circuit (ASIC) developed for a silicon Compton telescope. Composed of 32 channels, it reads out signals in both polarities from each side of a Silicon strip sensor, 2 mm thick 27 cm long, characterized by a strip capacitance of 30 pF. Each front-end channel provides low-noise charge amplification, shaping with a stabilized baseline, discrimination, and peak detection with an analog memory. The channels can process events simultaneously, and the read out is sparsified. The charge amplifier makes uses a dual-cascode configuration and dual-polarity adaptive reset, The low-hysteresis discriminator and the multi-phase peak detector process signals with a dynamic range in excess of four hundred. An equivalent noise charge (ENC) below 200 electrons was measured at 30 pF, with a slope of about 4.5 electrons/pF at a peaking time of 4 {micro}s. With a total dissipated power of 5 mW the channel covers an energy range up to 3.2 MeV.

Describes a computer simulation of the Compton effect designed to lead students to discover (1) the relationship of the electron's final kinetic energy to its angle of scattering and (2) the relationship between the scattering angles of the outgoing electron and photon. (MDH)

Compton scattering is the collision of photons and electrons. This collision causes the photons to be scattered with increased energy and therefore can produce high-energy photons. These high-energy photons can be used in many other fields including phase contrast medical imaging and x-ray structure determination. Compton scattering is currently well understood for low-energy collisions; however, in order to accurately compute spectra of backscattered photons at higher energies relativistic considerations must be included in the calculations. The focus of this work is to adapt a current program for calculating Compton backscattered radiation spectra to improve its efficiency. This was done by first translating the program from Matlab to python. The next step was to implement a more efficient adaptive integration to replace the trapezoidal method. A new program was produced that operates at less than a half of the speed of the original. This is important because it allows for quicker analysis, and sets the stage for further optimization. The programs were developed using just one particle, while in reality there are thousands of particles involved in these collisions. This means that a more efficient program is essential to running these simulations. The development of this new and efficient program will lead to accurate modeling of Compton sources as well as their improved performance.

The discovery of the Compton effect at the end of 1922 was a decisive event in the transition to the new quantum mechanics of 1925-1926 because it stimulated physicists to examine anew the fundamental problem of the interaction between radiation and matter. I first discuss Albert Einstein's light-quantum hypothesis of 1905 and why physicists greeted it with extreme skepticism, despite Robert A. Millikan's confirmation of Einstein's equation of the photoelectric effect in 1915. I then follow in some detail the experimental and theoretical research program that Arthur Holly Compton pursued between 1916 and 1922 at the University of Minnesota, the Westinghouse Lamp Company, the Cavendish Laboratory, and Washington University that culminated in his discovery of the Compton effect. Surprisingly, Compton was not influenced directly by Einstein's light-quantum hypothesis, in contrast to Peter Debye and H.A. Kramers, who discovered the quantum theory of scattering independently. I close by discussing the most significant response to that discovery, the Bohr-Kramers-Slater theory of 1924, its experimental refutation, and its influence on the emerging new quantum mechanics.

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. It consists of twelve high spectral resolution 3D Germanium Detectors that track gamma-ray Compton scatter interactions. Tracking technologies provide dramatic improvements in Compton efficiency and sensitivity: with less than 1% of the detector volume of COMPTEL, NCT achieves a similar effective area. NCT is breaking new ground in the measurement of polarized gamma-ray emission from astrophysical sources, while simultaneously providing a testing platform for novel event analysis, background reduction, and imaging techniques for modern Compton telescopes. NCT is currently being prepared for a 36-hour flight from New Mexico in September 2008, followed by a long duration flight from Australia in December 2009. On these science flights, NCT will map the galactic positron annihilation, Al-26, and Fe-60 emission, and perform a discovery study of polarization from all classes of gamma-ray sources. We will present an overview of the NCT instrument and the planned flight program.

Compton scattering is the process wherein photons scatter on the electrons within a material. In a detector, some of these scattered photons leave the detector with only part of their full energy. This creates a continuum which changes the signal to noise ratio with a gamma ray spectrum. For high resolution detectors such as high purity Ge (HPGe) solid state gamma ray detectors, a secondary detector surrounds the HPGe. The purpose of the secondary detector (made of a high Z material) is to detect the scattered photons. When both detectors have coincident photon events, a special circuit stops the data acquisition from acquiring the signal from the HPGe. Our goal is to design the optimal Compton ``suppressor'' using bismuth germinate scintillators for gamma rays whose energies are much larger than 1 MeV. Currently such suppressors are designed for energies less than 2 MeV. We are using the Monte Carlo N-particle code to calculate the amount of photon scattering in the HPGe into geometry of BGO surrounding the HPGe crystal. We are estimating both photon and electron fluence through the volume of BGO.

Over the past three years, a Compton spectrometer has successfully measured the x-ray spectra of intense radiographic sources. In this method, a collimated beam of x-rays incident on a convertor foil ejects Compton electrons. A collimator in the entrance to the spectrometer selects the forward-scattered electrons, which enter the magnetic field region of the spectrometer. The position of the electrons at the magnet's focal plane is proportional to the square root of their momentum, allowing the x-ray spectrum to be reconstructed. The spectrometer is a neodymium-iron magnet which measures spectra in the less than 1 MeV to 20 MeV energy range. In addition, a new spectrometer has been constructed that is a samarium-cobalt magnet with a calculated energy range of 50 keV to 4 MeV. The spectrometers have been fielded at both continuous and pulsed power facilities. Recent experimental results will be presented.

The scattering of a photon by an individual free electron is characterized by six quantities: ..cap alpha.. = initial photon energy in units of m/sub 0/c/sup 2/; ..cap alpha../sub s/ = scattered photon energy in units of m/sub 0/c/sup 2/; ..beta.. = initial electron velocity in units of c; phi = angle between photon direction and electron direction in the laboratory frame (LF); theta = polar angle change due to Compton scattering, measured in the electron rest frame (ERF); and tau = azimuthal angle change in the ERF. We present an analytic expression for the average of the Compton cross section over phi, theta, and tau. The lowest order approximation to this equation is reasonably accurate for photons and electrons with energies of many keV.

Various telescopes including RXTE, INTEGRAL, Suzaku, and Fermi have detected steady non-thermal X-ray emission in the 10 - 200 keV band from strongly magnetic neutron stars known as magnetars. Magnetic inverse Compton scattering is believed to be the leading candidate for the production of this intense X-ray radiation. Scattering at ultra-relativistic energies leads to attractive simplifications in the analytics of the magnetic Compton cross section. We have recently addressed such a case by developing compact analytic expressions using correct spin-dependent widths acquired through the implementation of Sokolov & Ternov basis states, focusing specifically on ground-state-ground-state scattering. Compton scattering in magnetar magnetospheres can cool electrons down to mildly relativistic energies. Moreover, soft gamma-ray flaring in magnetars may involve strong Comptonization in expanding clouds of mildly relativistic pairs. Such environs necessitate the development of more general magnetic scattering cross sections, in which the incoming photons acquire substantial incident angles relative to the field in the rest frame of the electron leading to arbitrary Landau excitations of the intermediate and final states. Due to the rapid transitions of the excited-state to the ground-state, the initial electron is still assumed to be in the ground state. The cross sections treat the plethora of harmonic resonances associated with various cyclotron transitions between Landau states. Polarization and spin dependence of the cross section for the four scattering modes is compared to the cross section obtained with spin-averaged widths. We present numerical results to show the comparisons to highlight the role of the spin-dependent widths of the resonances. The findings presented here will have applications to various neutron star problems, including computation of Eddington luminosities and polarization mode-switching rates in transient magnetar fireballs.

In Compton scattering light sources, a laser pulse is scattered by a relativistic electron beam to generate tunable x and gamma rays. Because of the inhomogeneous nature of the incident radiation, the relativistic Lorentz boost of the electrons is modulated by the ponderomotive force during the interaction, leading to intrinsic spectral broadening and brightness limitations. We discuss these effects, along with an optimization strategy to properly balance the laser bandwidth, diffraction, and nonlinear ponderomotive force.

Virtual Compton Scattering o013 the proton has been studied at Q 2 -values of 1:0 and 1:9 (GeV=c) 2 in Hall A at the Thomas Je013erson National Accelerator Facility (JLab). Data were taken below and above the pion production threshold as well as in the resonance region. Results obtained below pion threshold at Q 2 = 1:0 (GeV=c) 2 are presented in this paper.

We have been developing a multi-layer Compton Gamma Ray Imager using position-sensitive, intrinsic silicon detectors. Advantages of this approach include room temperature operation, reduced Doppler broadening, and use of conventional silicon fabrication technologies. We have obtained results on the imaging performance of a multi-layer instrument where each layer consists of a 2×2 array of double-sided strip detectors. Each detector is 63 mm×63 mm×2 mm thick and has 64 strips providing a strip pitch of approximately 0.9 mm. The detectors were fabricated by SINTEF ICT (Oslo Norway) from 100 mm diameter wafers. The use of large arrays of silicon detectors appears especially advantageous for applications that require excellent sensitivity, spectral resolution and imaging such as gamma ray astrophysics, detection of special nuclear materials, and medical imaging. The multiple Compton interactions (three or more) in the low-Z silicon enable the energy and direction of the incident gamma ray to be determined without full deposition of the incident gamma-ray energy in the detector. The performance of large volume instruments for various applications are presented, including an instrument under consideration for NASA's Advanced Compton Telescope (ACT) mission and applications to Homeland Security. Technology developments that could further extend the sensitivity and performance of silicon Compton Imagers are presented, including the use of low-energy (few hundred keV) electron tracking within novel silicon detectors and the potential for a wafer-bonding approach to produce thicker, position-sensitive silicon detectors with an associated reduction of required electronics and instrument cost.

The beam spin asymmetries of the reaction ep -> epg in the Bjorken regime were measured over a wide kinematical domain using the CLAS detector and a new lead-tungstate calorimeter. Through the interference of the Bethe-Heitler process with Deeply Virtual Compton Scattering, those asymmetries provide constraints for the nucleon Generalized Parton Distributions models. The observed shapes are in agreement with twist-2 dominance predictions.

In Compton scattering light sources, a laser pulse is scattered by a relativistic electron beam to generate tunable x and gamma rays. Because of the inhomogeneous nature of the incident radiation, the relativistic Lorentz boost of the electrons is modulated by the ponderomotive force during the interaction, leading to intrinsic spectral broadening and brightness limitations. These effects are discussed, along with an optimization strategy to properly balance the laser bandwidth, diffraction, and nonlinear ponderomotive force.

Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for the study of the partonic structure of hadrons, within the universal framework of generalized parton distributions (GPDs). This paper presents the aim and general ideas of the DVCS experimental program off nuclei at the Jefferson Laboratory. The benefits of the study of the coherent and incoherent channels to the understanding of the EMC (European Muon Collaboration) effect are discussed, along with the case of nuclear targets to access neutron GPDs.

The distribution of the parton content of nuclei, as encoded via the generalized parton distributions (GPDs), can be accessed via the deeply virtual Compton scattering (DVCS) process contributing to the cross section for leptoproduction of real photons. Similarly to the scattering of light by a material, DVCS provides information about the dynamics and the spatial structure of hadrons. The sensitivity of this process to the lepton beam polarization allows to single-out the DVCS amplitude in terms of Compton form factors that contain GPDs information. The beam spin asymmetry of the $^4$He($\\vec {\\mathrm e}$,e$' \\gamma ^4$He) process was measured in the experimental Hall B of the Jefferson Laboratory to extract the real and imaginary parts of the twist-2 Compton form factor of the $^4$He nucleus. The experimental results reported here demonstrate the relevance of this method for such a goal, and suggest the dominance of the Bethe-Heitler amplitude to the unpolarized process in the kinematic range explored by the experiment.

Compton scattering plays an important role in various astrophysical objects such as accreting black holes and neutron stars, pulsars, relativistic jets, and clusters of galaxies, as well as the early universe. In most of the calculations, it is assumed that the electrons have isotropic angular distribution in some frame. However, there are situations where the anisotropy may be significant due to the bulk motions, or where there is anisotropic cooling by synchrotron radiation or an anisotropic source of seed soft photons. Here we develop an analytical theory of Compton scattering by anisotropic distribution of electrons that can significantly simplify the calculations. Assuming that the electron angular distribution can be represented by a second-order polynomial over the cosine of some angle (dipole and quadrupole anisotropies), we integrate the exact Klein-Nishina cross section over the angles. Exact analytical and approximate formulae valid for any photon and electron energies are derived for the redistribution functions describing Compton scattering of photons with arbitrary angular distribution by anisotropic electrons. The analytical expressions for the corresponding photon scattering cross section on such electrons, as well as the mean energy of scattered photons, its dispersion, and radiation pressure force are also derived. We apply the developed formalism to the accurate calculations of the thermal and kinematic Sunyaev-Zeldovich effects for arbitrary electron distributions.

The next generation of space telescopes utilizing Compton scattering for astrophysical observations is destined to one day unravel the mysteries behind Galactic nucleosynthesis, to determine the origin of the positron annihilation excess near the Galactic center, and to uncover the hidden emission mechanisms behind gamma-ray bursts. Besides astrophysics, Compton telescopes are establishing themselves in heliophysics, planetary sciences, medical imaging, accelerator physics, and environmental monitoring. Since the COMPTEL days, great advances in the achievable energy and position resolution were possible, creating an extremely vast, but also extremely sparsely sampled data space. Unfortunately, the optimum way to analyze the data from the next generation of Compton telescopes has not yet been found, which can retrieve all source parameters (location, spectrum, polarization, flux) and achieves the best possible resolution and sensitivity at the same time. This is especially important for all sciences objectives looking at the inner Galaxy: the large amount of expected sources, the high background (internal and Galactic diffuse emission), and the limited angular resolution, make it the most taxing case for data analysis. In general, two key challenges exist: First, what are the best data space representations to answer the specific science questions? Second, what is the best way to deconvolve the data to fully retrieve the source parameters? For modern Compton telescopes, the existing data space representations can either correctly reconstruct the absolute flux (binned mode) or achieve the best possible resolution (list-mode), both together were not possible up to now. Here we propose to develop a two-stage hybrid reconstruction method which combines the best aspects of both. Using a proof-of-concept implementation we can for the first time show that it is possible to alternate during each deconvolution step between a binned-mode approach to get the flux right and a

Spin momentum density of Nd has been measured at 6K temperature using magnetic Compton scattering. The individual contribution of different electronic states, in the formation of total spin moment, is deduced from the analysis of magnetic Compton profile. The electron-specific spin moments deduced from the experimental Compton data are compared with the theoretical results obtained from full potential linearized augmented plane wave method and are found to be in good agreement.

Three major accomplishments resulted from this effort: (1) It was determined that the Machine Vision Fire Detection System (MVFDS) could be augmented with a near-infrared imaging FPA/CCD, 4-8 IR transmitting optic waveguides, and modified algorithms to measure small changes in temperature of small areas on the engine casing and therefore determine overheat condition and/or possible burn-through condition. The IR-MVFDS would also detect small burn-through torch-like fires as well as nacelle fires associated with munitions and leaking/broken fuel and hydraulic lines. (2) Tests verified the ability of the visible MVFDS flame detector to simultaneously detect smoke and measure its transmissivity. This dual function, in addition to possibly as many as 16 or more separate fields-of-view using small fiber optic cables, makes the Smoke/Flame-MVFDS cost effective in aircraft and in commercial applications. (3) The potential benefits and cost savings of both the IR-MVFDS and Smoke/Flame-MVFDS were demonstrated. The technical basis was proven feasible with minimum risk for development of both the IR-MVFDS and the Flame/Smoke-MVFDS in Phase II.

The present study is focused on the application of recovered coagulant (RC) by acidification from drinking water treatment residuals for both adjusting the initial pH and aiding coagulant in electrocoagulation. To do this, real cotton textile wastewater was used as a target pollutant, and decolorization and chemical oxygen demand (COD) removal efficiency were monitored. A preliminary test indicated that a stainless steel electrode combined with RC significantly accelerated decolorization and COD removal efficiencies, by about 52% and 56%, respectively, even at an operating time of 5 min. A single electrocoagulation system meanwhile requires at least 40 min to attain the similar removal performances. Subsequently, the interactive effect of three independent variables (applied voltage, initial pH, and reaction time) on the response variables (decolorization and COD removal) was evaluated, and these parameters were statistically optimized using the response surface methodology. Analysis of variance showed a high coefficient of determination values (decolorization, R(2) = 0.9925 and COD removal, R(2) = 0.9973) and satisfactory prediction second-order polynomial quadratic regression models. Average decolorization and COD removal of 89.52% and 94.14%, respectively, were achieved, corresponding to 97.8% and 98.1% of the predicted values under statistically optimized conditions. The results suggest that the RC effectively played a dual role of both adjusting the initial pH and aiding coagulant in the electrocoagulation process.

The origin of the high-energy component in spectral energy distributions (SEDs) of blazars is still something of a mystery. While BL Lac objects can be successfully modeled within the one-zone synchrotron self-Compton (SSC) scenario, the SED of low-peaked flat spectrum radio quasars is more difficult to reproduce. Their high-energy component needs the abundance of strong external photon sources, giving rise to stronger cooling via the inverse Compton (IC) channel, and thus to a powerful component in the SED. Recently, we have been able to show that such a powerful inverse Compton component can also be achieved within the SSC framework. This, however, is only possible if the electrons cool by SSC, which results in a nonlinear process, since the cooling depends on an energy integral over the electrons. In this paper, we aim to compare the nonlinear SSC framework with the external Compton (EC) output by calculating analytically the EC component with the underlying electron distribution being either linearly or nonlinearly cooled. Due to the additional linear cooling of the electrons with the external photons, higher number densities of electrons are required to achieve nonlinear cooling, resulting in more powerful IC components. If the electrons initially cool nonlinearly, the resulting SED can exhibit a dominant SSC over the EC component. However, this dominance depends strongly on the input parameters. We conclude that, with the correct time-dependent treatment, the SSC component should be taken into account in modeling blazar flares.

Deeply Virtual Compton Scattering (DVCS) is the tool of choice to study Generalized Parton Distributions (GPD) in the nucleon. After a general introduction to the subject, a review of experimental results from various facilities is given. Following the first encouraging results, new generation dedicated experiments now allow unprecedented precision and kinematical coverage. Several new results were presented during the conference, showing significant progress in this relatively new field. Prospects for future experiments are presented. The path for the experimental determination of GPDs appears now open.

Neutron Compton scattering (NCS) can be applied to measuring nuclear momentum distributions and potential parameters in molecules of biophysical interest. We discuss the analysis of NCS spectra from peptide models, focusing on the characterisation of the amide proton dynamics in terms of the width of the H-bond potential well, its Laplacian, and the mean kinetic energy of the proton. The Sears expansion is used to quantify deviations from the high-Q limit (impulse approximation), and line-shape asymmetry parameters are evaluated in terms of Hermite polynomials. Results on NCS from selectively deuterated acetanilide are used to illustrate this approach.

Incoherent X-ray scattering spectra of diamond and silicon crystals recorded on the BESSY-2 electron storage ring have been analyzed. All spectral features are described well in terms of the neoclassical scattering theory without consideration for the hypotheses accepted in quantum electrodynamics. It is noted that the accepted tabular data on the intensity ratio between the Compton and Rayleigh spectral components may significantly differ from the experimental values. It is concluded that the development of the general theory (considering coherent scattering, incoherent scattering, and Bragg diffraction) must be continued.

We have studied how often incoming photons interact via a Compton interaction and/or a photoelectric interaction as a function of energy and detector material Results are using a 1m{sup 3} detector, and discrete energy photons from 0.1 MeV up to 10 MeV. Essentially all of the lower energy photons interact at least once in a detector of this size. This is not the case at higher energies. Each detector, photon energy combination was simulated with 2000 photons.

To build upon the goals of the upcoming INTEGRAL mission, the next generation soft γ-ray (0.2-20 MeV) observatory will require improved sensitivity to nuclear line emission while maintaining high spectral resolution. We present the simulated performance of a germanium Compton telescope (GCT) design, which will allow a factor of ten improvement in sensitivity over INTEGRAL/SPI. We also discuss a number of issues concerning reconstruction techniques and event cuts, and demonstrate how these affect the overall performance of the telescope.

The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e-vector,e{sup '}{gamma})X cross section measured at Q{sup 2}=1.9 GeV{sup 2} and x{sub B}=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E{sub q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

Extended inverse Compton halos are generally anticipated around extragalactic sources of gamma rays with energies above 100 GeV. These result from inverse Compton scattered cosmic microwave background photons by a population of high-energy electron/positron pairs produced by the annihilation of the high-energy gamma rays on the infrared background. Despite the observed attenuation of the high-energy gamma rays, the halo emission has yet to be directly detected. Here, we demonstrate that in most cases these halos are expected to be highly anisotropic, distributing the upscattered gamma rays along axes defined either by the radio jets of the sources or oriented perpendicular to a global magnetic field. We present a pedagogical derivation of the angular structure in the inverse Compton halo and provide an analytic formalism that facilitates the generation of mock images. We discuss exploiting this fact for the purpose of detecting gamma-ray halos in a set of companion papers.

A dosimetry technique for high-energy gamma radiation or X-radiation employs the Compton effect in conjunction with radiation-induced thermally activated depolarization phenomena. A dielectric material is disposed between two electrodes which are electrically short circuited to produce a dosimeter which is then exposed to the gamma or X radiation. The gamma or X-radiation impinging on the dosimeter interacts with the dielectric material directly or with the metal composing the electrode to produce Compton electrons which are emitted preferentially in the direction in which the radiation was traveling. A portion of these electrons becomes trapped in the dielectric material, consequently inducing a stable electrical polarization in the dielectric material. Subsequent heating of the exposed dosimeter to the point of onset of ionic conductivity with the electrodes still shorted through an ammeter causes the dielectric material to depolarize, and the depolarization signal so emitted can be measured and is proportional to the dose of radiation received by the dosimeter.

Previous work on calculating energy spectra from Compton scattering events has either neglected considering the pulsed structure of the incident laser beam, or has calculated these effects in an approximate way subject to criticism. In this paper, this problem has been reconsidered within a linear plane wave model for the incident laser beam. By performing the proper Lorentz transformation of the Klein-Nishina scattering cross section, a spectrum calculation can be created which allows the electron beam energy spread and emittance effects on the spectrum to be accurately calculated, essentially by summing over the emission of each individual electron. Such an approach has the obvious advantage that it is easily integrated with a particle distribution generated by particle tracking, allowing precise calculations of spectra for realistic particle distributions "in collision." The method is used to predict the energy spectrum of radiation passing through an aperture for the proposed Old Dominion University inverse Compton source. Many of the results allow easy scaling estimates to be made of the expected spectrum.

The generalized parton distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply virtual Compton scattering (DVCS) on a proton or neutron ($N$), $e N \\rightarrow e' N' \\gamma$, is the process more directly interpretable in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, the process where a photon is emitted by either the incident or scattered electron, can be accessed via cross-section measurements or exploiting their interference which gives rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading-twist GPDs (${H}$, ${E}$, ${\\tilde{H}}$, ${\\tilde{E}}$) for each quark flavors, depending on the observable and on the type of target. This paper gives an overview of recent experimental results obtained for DVCS at Jefferson Laboratory in the halls A and B. Several experiments have been done extracting DVCS observables over large kinematics regions. Multiple measurements with overlapping kinematic regions allow to perform a quasi-model independent extraction of the Compton form factors, which are GPDs integrals, revealing a 3D image of the nucleon.

The European Muon Collaboration (EMC) observed the first signs of a modification of the partonic structure of the nucleon when present in a nuclear medium. The precise nature of these effects, as well as their underlying cause, is yet to be determined. The generalized parton distribution (GPD) framework provides a powerful tool to study the partonic structure of nucleons inside a nucleus. Hard exclusive leptoproduction of a real photon off a nucleon, deeply virtual Compton scattering (DVCS), is presently considered the cleanest experimental access to the GPDs, through the Compton form factors (CFFs). This is especially the case for scattering off the spin-zero helium nucleus, where only a single CFF contributes to the process. The real and imaginary parts of this CFF can be constrained through the beam-spin asymmetry (BSA). We will present the first measurements of the DVCS process off 4He using the CEBAF 6 GeV polarized electron beam and the CLAS detector at JLab. The CLAS detector was supplemented with an inner electromagnetic calorimeter for photons produced at small angles, as well as a radial time projection chamber (RTPC) to detect low-energy recoil nuclei. This setup allowed for a clean measurement of the BSA in both the coherent and incoherent channels.

A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

Here, Compton scattering techniques have been developed for accurate measurements of densities and temperatures in dense plasmas. One future challenge is the application of this technique to characterize compressed matter on the National Ignition Facility where hydrogen and beryllium will approach extremely dense states of matter of up to 1000 g/cc. In this regime, the density, compressibility, and capsule fuel adiabat may be directly measured from the Compton scattered spectrum of a high-energy x-ray line source. Specifically, the scattered spectra directly reflect the electron velocity distribution. In non-degenerate plasmas, the width provides an accurate measure of the electron temperatures, whilemore » in partially Fermi degenerate systems that occur in laser-compressed matter it provides the Fermi energy and hence the electron density. Both of these regimes have been accessed in experiments at the Omega laser by employing isochorically heated solid-density beryllium and moderately compressed beryllium foil targets. In the latter experiment, compressions by a factor of 3 at pressures of 40 Mbar have been measured in excellent agreement with radiation hydrodynamic modeling.« less

We study elastic Compton scattering on 3He using chiral effective field theory (χEFT) at photon energies from 60 MeV to approximately 120 MeV. Experiments to measure this process have been proposed for both MAMI at Mainz and the HI γS facility at TUNL. I will present the revised results of a full calculation at third order in the expansion (O (Q3)). The amplitude involves a sum of both one- and two-nucleon Compton-scattering mechanisms. We have recently computed the fourth-order two-nucleon diagrams. The numerical impact they have on the cross-section results will be discussed. I will also present results in which amplitudes used so far are augmented by the leading effects from Δ (1232) degrees of freedom, a step which has already been performed for the proton and deuteron processes. Both cross sections and doubly-polarized asymmetries will be presented, and the sensitivity of these observables to the values of neutron scalar and spin polarizabilities will be assessed. This material is based upon work supported in part by DOE and George Washington University.

During the previous three years, a Compton spectrometer has successfully measured the x-ray spectra of both continuous and flash radiographic sources. In this method, a collimated beam of x-rays incident on a convertor foil ejects Compton electrons. A collimator in the entrance to the spectrometer selects the forward-scattered electrons, which enter the magnetic field region of the spectrometer. The position of the electrons at the magnet's focal plane is proportional to the square root of their momentum, allowing the x-ray spectrum to be reconstructed. The spectrometer is a neodymium-iron magnet which measures spectra in the <1 MeV to 20 MeV energy range. The energy resolution of the spectrometer was experimentally tested with the 44 MeV Short-Pulse Electron LINAC at the Idaho Accelerator Center. The measured values are mostly consistent with the design specification and historical values of the greater of 1% or 0.1 MeV. Experimental results from this study are presented in these proceedings.

A high-intensity, inexpensive and collimated x-ray source is disclosed for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications. 4 figs.

A new series of primary ammonium monocarboxylate (PAM) salts of a nonsteroidal anti-inflammatory drug (NSAID), namely, tolfenamic acid (TA), and its β-alanine derivatives were generated. Nearly 67 % of the salts in the series showed gelling abilities with various solvents, including water (biogenic solvent) and methyl salicylate (typically used for topical gel formulations). Gels were characterized by rheology, electron microscopy, and so forth. Structure-property correlations based on single-crystal and powder XRD data of several gelator and nongelator salts revealed intriguing insights. Studies (in vitro) on an aggressive human breast cancer cell line (MDA-MB-231) with the l-tyrosine methyl ester salt of TA (S7) revealed that the hydrogelator salt was more effective at killing cancer cells than the mother drug TA (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay); displayed better anti-inflammatory activity compared with that of TA (prostaglandin E2 assay); could be internalized within the cancer cells, as revealed by fluorescence microscopy; and inhibited effectively migration of the cancer cells. Thus, the easily accessible ambidextrous gelator salt S7 can be used for two purposes: as an anti-inflammatory topical gel and as an anticancer agent.

In this paper, we develop the extended jet model of Potter & Cotter to model the simultaneous multiwavelength spectra of six Compton-dominant blazars. We include an accelerating parabolic base transitioning to a slowly decelerating conical jet with a geometry set by observations of M87 and consistent with simulations and theory. We investigate several jet models and find that the optically thick to thin synchrotron break in the radio spectrum requires the jet to first come into equipartition at large distances along the jet, consistent with the observed transition from parabolic to conical at 105Rs in the jet of M87. We confirm this result analytically and calculate the expected frequency core-shift relations for the models under consideration. We find that a parabolic jet transitioning to a ballistic conical jet at 105Rs, which starts in equipartition and becomes more particle dominated at larger distances, fits the multiwavelength data of the six blazars well, whilst an adiabatic equipartition conical section requires very large bulk Lorentz factors to reproduce the Compton dominance of the blazars. We find that all these blazars require high power (>1039 W), high bulk Lorentz factor (>20) jets observed close to the line of sight (<2°) as we expect from the blazar sequence and consistent with the results from Paper II. The inverse-Compton emission in our fits is due to inverse-Compton scattering of high-redshift cosmic microwave background photons at large distances along the jet due to the high bulk Lorentz factors of the jets. We postulate a new interpretation of the blazar sequence based on the radius of the transition region of the jet (where the jet is brightest in synchrotron emission) scaling linearly with black hole mass.

We show that the sharp cutoff in the hard X-ray spectrum of NGC 4151, unusual for Seyfert 1 galaxies, can be reconciled with the average Seyfert 1 spectrum if we assume that the central source is completely hidden from our line of sight by the thick part of the accretion disk or by the broad emission-line clouds. The observed X-ray radiation is produced by scattering of the Seyfert 1 type spectrum in the higher, cooler parts of the accretion disk corona, or in a wind. A sharp cutoff appears as a result of the Compton recoil effect. This model naturally explains a discrepancy regarding the inclination of the central source, inferred to be low (face-on) from observations of the iron K-alpha emission line, but inferred to be high on the basis of optical and UV observations.

In this sketch, some recent developments in Compton scattering off the deuteron are reviewed. The strong energy-dependence of the scalar magnetic dipole polarisability βM1 turns out to be crucial to understand the data from Saskatoon at 94 MeV. Chiral Effective Field Theory is used to extract the static iso-scalar dipole polarisabilities as ᾱs = 12.6 ± 1.4stat ± 1.0wavefu and β¯s = 2.3 ± 1.7stat ± 0.8wavefu, in units of 10-4 fm3. Therefore, proton and neutron polarisabilities are identical within error bars. For details and a better list of references, consult e.g. Refs. [1, 2].

We compute the dynamics and emission of dissipative shells that are subject to a strong Compton drag, under simplifying assumptions about the dissipation mechanism. We show that under conditions prevailing in blazars, substantial deceleration is anticipated on sub-parsec and parsec scales in cases of rapid dissipation. Such episodes may be the origin of some of the flaring activity occasionally observed in gamma-ray blazars. The shape of the light curves thereby produced reflects the geometry of the emitting surface if the deceleration is very rapid, or the dynamics of the shell if the deceleration is delayed, or initially more gradual, owing, e.g., to continuous injection of energy and momentum.

We investigate the Compton scattering vertex of charged scalars and photons in scalar quantum electrodynamics (SQED). We carry out its nonperturbative construction consistent with Ward-Fradkin-Green-Takahashi identity which relates 3-point vertices to the 4-point ones. There is an undetermined part which is transverse to one or both the external photons, and needs to be evaluated through perturbation theory. We present in detail how the transverse part at the 1-loop order can be evaluated for completely general kinematics of momenta involved in covariant gauges and dimensions. This involves the calculation of genuine 4-point functions with three massive propagators, the most nontrivial integrals reported in this paper. We also discuss possible applications of our results.

Compton inverse radiation is emitted in the process of backscattering of the laser pulses off the relativistic electrons. This radiation possesses high spectral density and high energy of photons--in hard x-ray up to gammaray energy range--with moderate electron energies (hundreds of MeV up to 1 GeV) due to short wavelength of the laser radiation. The Compton radiation is well collimated: emitting within a narrow cone along the electron beam. A distinct property of the Compton inverse radiation is a steep high-energy cutoff of the spectrum and the maximal intensity just below the cutoff. The Compton sources can attain: spectral density up to 1014 gammas/(s 0.1%bandwidth) in MeV range of energies, and spectral brightness up to 1020 gammas/(smm2mr2 0.1% bw). Applicability of Compton sources for nuclear waste management and detection of radioisotopes and fissionable nuclides are discussed in the report. Also application limits of Compton gamma sources for transmutation of radioactive isotopes are estimated. A recently proposed subtracting method, in which two sets of data obtained by irradiating the object by the Compton beams with slightly different maximal energies are compared, will enhance resolution of detection radioactive elements at the 'atomic' (hundreds of keV) and the 'nuclear' (a few MeV) photon energies.

Compton backscattering polarimetry provides a fast measurement of the polarization of an electron beam in a storage ring. Since the method is non-destructive, the polarization of the electrons can be monitored during internal target experiments. At NIKHEF a Compton polarimeter has been constructed to measure the polarization of the longitudinally polarized electrons stored in the AmPS ring. First results obtained with the polarimeter, the first Compton polarimeter to measure the polarization of a stored longitudinally polarized electron beam, are presented in this paper.

Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV-200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

We built and commissioned a new type of Compton polarimeter to measure the electron beam polarization at the Thomas Jefferson National Accelerator Facility (Virginia, USA). The heart of this polarimeter is a high-finesse monolithic Fabry-Perot cavity. Its purpose is to amplify a primary 300 mW laser beam in order to improve the signal to noise ratio of the polarimeter. It is the first time that a high-finesse Fabry-Perot cavity is enclosed in the vacuum of a particle accelerator to monitor the beam polarization by Compton polarimetry. The measured finesse and amplification gain of the cavity are F=26000 and G=7300. The electron beam crosses this high-power photon source at an angle of 23 mrad in the middle of the cavity where the photon beam power density is estimated to be 0.85MW/cm2. We have used this facility during the HAPPEX experiment (April-July 1999) and we give a preliminary measurement of Compton scattering asymmetry.

Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV–200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

The nonlinear Compton scattering rate in a rotating electric field is explicitly calculated. For this purpose, an approximate solution to the Klein-Gordon equation in the presence of a rotating electric field is applied. An analytical expression for the emission rate is obtained, as well as a simplified approximation adequate for implementation in kinetic codes. The spectrum is numerically calculated for present-day optical and x-ray laser parameters. The results are compared to the standard Volkov-Ritus rate for a particle in a plane wave, which is commonly assumed to be valid for a rotating electric field under certain conditions. Substantial deviations between the two models, in both the radiated power and the spectral shape, are demonstrated. First, the typical number of photons participating in the scattering process is much smaller compared to the Volkov-Ritus rate, resulting in up to an order of magnitude lower emitted power. Furthermore, our model predicts a discrete harmonic spectrum for electrons with low asymptotic momentum compared to the field amplitude. This discrete structure is a clear imprint of the electric field frequency, as opposed to the Volkov-Ritus rate, which reduces to the constant crossed field rate for the physical conditions under consideration. Our model predictions can be tested with present-day laser facilities.

This review discusses the principles and technological realisation of a technique, termed Compton scatter imaging (CSI), which is based on spatially resolved detection of Compton scattered X-rays. The applicational focus of this review is to objects of historical interest. Following a historical survey of CSI, a description is given of the major characteristics of Compton X-ray scatter. In particular back-scattered X-rays allow massive objects to be imaged, which would otherwise be too absorbing for the conventional transmission X-ray technique. The ComScan (an acronym for Compton scatter scanner) is a commercially available backscatter imaging system, which is discussed here in some detail. ComScan images from some artefacts of historical interest, namely a fresco, an Egyptian mummy and a mediaeval clasp are presented and their use in historical analysis is indicated. The utility of scientific and technical advance for not only exploring history, but also restoring it, is briefly discussed.

The Compton scattering measurement on intermetallic alloy Ti{sub 3}Al is reported in this work. The measurement is made using 59.54 keV gamma-rays from Am{sup 241} source. Theoretical calculation of Compton profile is also performed employing CRYSTAL code within the framework of density functional theory to compare with the measurement. The theoretical profile of the alloy is also synthesized following the superposition model taking the published Compton profiles of elemental solids from the APW method. The experimental study of charge transfer in the alloys has also been done by performing the experimental Compton profile measurements on Ti and Al following the superposition model and charge transfer from Al to Ti is clearly seen on the alloy formation.

This fastener used in induction heating is a wire screen basically of an eddy current carrying material such as carbon steel. Selected wires in the screen are copper, sheathed in an insulating material. The screen is placed between two sheets of thermoplastics. When inductively heated, the composite softens and flows around the apertures of the screen. After this heating and joining, the copper wires may be used to conduct electricity.

It is common for freshmen students to enter Calculus I with a wide range of levels of preparation and mastery of background material. In addition, many of the students struggle with the adjustment from high school to college. In an effort to help the students to solidify their understanding of concepts as they progress through the course, as well…

This patent describes a method for inhibiting the nitrification of ammonium nitrogen resulting from the inclusion of ammonia or ammonium-containing fertilizers to nitrite and nitrate at a situs, the situs including soil systems. It comprises: exposing soil containing nitrifying organisms at the situs to relatively small predetermined amounts of thiophosphoryl triamide. The method is characterized by the fact that loss from the situs of fertilizer nitrogen values by leaching and denitrification therefrom and the resulting potential for groundwater pollution by the leaching and atmospheric pollution by the denitrification is eliminated or substantially reduced.

We present a new theoretical approach to attosecond laser-assisted photo- and Compton ionization. Attosecond x-ray absorption and scattering are described by \\hat{\\mathscr{S}}^{(1,2)} -matrices, which are coherent superpositions of 'monochromatic' \\skew{3}\\hat{S}^{(1,2)} -matrices in a laser-modified Furry representation. Besides refining the existing theory of the soft x-ray photoelectron attosecond streak camera and spectral phase interferometry (ASC and ASPI), we formulate a theory of hard x-ray photoelectron and Compton ASC and ASPI. The resulting scheme has a simple structure and leads to closed-form expressions for ionization amplitudes. We investigate Compton electron interference in the separable Coulomb-Volkov continuum with both Coulomb and laser fields treated non-perturbatively. We find that at laser-field intensities below 1013 Wcm-2 normalized Compton lines almost coincide with the lines obtained in the laser-free regime. At higher intensities, attosecond interferences survive integration over electron momenta, and feature prominently in the Compton lines themselves. We define a regime where the electron ground-state density can be measured with controllable accuracy in an attosecond time interval. The new theory provides a firm basis for extracting photo- and Compton electron phases and atomic and molecular wavefunctions from experimental data.

The Arthur Holly Compton Gamma Ray Observatory (GRO) was launched by the shuttle Atlantis in April 1991. This paper presents the results of the attitude sensor calibration that was performed during the early mission. The GSFC Flight Dynamics Facility (FDF) performed an alignment calibration of the two fixed-head star trackers (FHST's) and two fine Sun sensors (FSS's) on board Compton GRO. The results show a 27-arcsecond shift between the bore sights of the FHST's with respect to prelaunch measurements. The alignments of the two FSS's shifted by 0.20 and 0.05 degree. During the same time period, the Compton GRO science teams performed an alignment calibration of the science instruments with respect to the attitude reported by the on board computer (OBC). In order to preserve these science alignments, FDF adjusted the overall alignments of the FHST's and FSS's, obtained by the FDF calibration, such that when up linked to the OBC, the shift in the OBC-determined attitude is minimized. FDF also calibrated the inertial reference unit (IRU), which consists of three dual-axis gyroscopes. The observed gyro bias matched the bias that was solved for by the OBC. This bias drifted during the first 6 days after release. The results of the FDF calibration of scale factor and alignment shifts showed changes that were of the same order as their uncertainties.

The Arthur Holly Compton Gamma Ray Observatory (GRO) was launched by the shuttle Atlantis in April 1991. This paper presents the results of the attitude sensor calibration that was performed during the early mission. The GSFC Flight Dynamics Facility (FDF) performed an alignment calibration of the two fixed-head star trackers (FHST's) and two fine Sun sensors (FSS's) on board Compton GRO. The results show a 27-arcsecond shift between the bore sights of the FHST's with respect to prelaunch measurements. The alignments of the two FSS's shifted by 0.20 and 0.05 degree. During the same time period, the Compton GRO science teams performed an alignment calibration of the science instruments with respect to the attitude reported by the on board computer (OBC). In order to preserve these science alignments, FDF adjusted the overall alignments of the FHST's and FSS's, obtained by the FDF calibration, such that when up linked to the OBC, the shift in the OBC-determined attitude is minimized. FDF also calibrated the inertial reference unit (IRU), which consists of three dual-axis gyroscopes. The observed gyro bias matched the bias that was solved for by the OBC. This bias drifted during the first 6 days after release. The results of the FDF calibration of scale factor and alignment shifts showed changes that were of the same order as their uncertainties.

The principle of the compact Compton source is presented briefly. In collision with an ultrarelativistic electron bunch a laser pulse is back-scattered as hard X-rays. The radiation cone has an opening of a few mrad, and the energy bandwidth is a few percent. The electrons that have an energy of the order of a few tens of MeV either circulate in storage ring, or are injected to a linac at a frequency of 10-100 MHz. At the interaction point the electron bunch collides with the laser pulse that has been amplified in a Fabry-Perot resonator. There are several machines in design or construction phase, and projected fluxes are 10(12) to 10(14) photons/s. The flux available at 80 keV from the ThomX machine is compared with that used in the Stereotactic Synchrotron Radiation Therapy clinical trials. It is concluded that ThomX has the potential of serving as the radiation source in future radiation therapy programs, and that ThomX can be integrated in hospital environment.

Pulmonary edema is the pathological increase of extravascular lung water found most often in patients with congestive heart failure and other critically ill patients who suffer from intravenous fluid overload. A non-invasive lung density monitor that is accurate, easily portable, safe and inexpensive is needed for clinical evaluation of pulmonary edema. Other researchers who have employed Compton scattering techniques generally used systems of extended size and detectors with poor energy resolution. This has resulted in significant systematic biases from multiply-scattered photons and larger errors in counting statistics at a given radiation dose to the patient. We are proposing a patented approach in which only backscattered photons are measured with a high-resolution HPGe detector in a compact system geometry. By proper design and a unique data extraction scheme, effects of the variable chest wall on lung density measurements are minimized. Preliminary test results indicate that with a radioactive source of under 30 GBq, it should be possible to make an accurate lung density measurement in one minute, with a risk of radiation exposure to the patient a thousand times smaller than that from a typical chest x-ray. The ability to make safe, frequent lung density measurements could be very helpful for monitoring the course of P.E. at the hospital bedside or outpatient clinics, and for evaluating the efficacy of therapy in clinical research. 6 refs., 5 figs.

A Compton camera is being developed for the purpose of ion-range monitoring during hadrontherapy via the detection of prompt-gamma rays. The system consists of a scintillating fiber beam tagging hodoscope, a stack of double sided silicon strip detectors (90×90×2 mm3, 2×64 strips) as scatter detectors, as well as bismuth germanate (BGO) scintillation detectors (38×35×30 mm3, 100 blocks) as absorbers. The individual components will be described, together with the status of their characterization.

Compton scattering is the nonresonant inelastic scattering of an x-ray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high x-ray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom. As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL–matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible. , which features invited work from the best early-career researchers working within the scope of J. Phys. B. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Sang-Kil Son was selected by the Editorial Board of J. Phys. B as an Emerging Leader.

We investigated the effect of inverse Compton scattering in mildly relativistic static and moving plasmas with low optical depth using Monte Carlo simulations, and calculated the Sunyaev-Zel'dovich effect in the cosmic background radiation. Our semi-analytic method is based on a separation of photon diffusion in frequency and real space. We use Monte Carlo simulation to derive the intensity and frequency of the scattered photons for a monochromatic incoming radiation. The outgoing spectrum is determined by integrating over the spectrum of the incoming radiation using the intensity to determine the correct weight. This method makes it possible to study the emerging radiation as a function of frequency and direction. As a first application we have studied the effects of finite optical depth and gas infall on the Sunyaev-Zel'dovich effect (not possible with the extended Kompaneets equation) and discuss the parameter range in which the Boltzmann equation and its expansions can be used. For high temperature clusters (k(sub B)T(sub e) greater than or approximately equal to 15 keV) relativistic corrections based on a fifth order expansion of the extended Kompaneets equation seriously underestimate the Sunyaev-Zel'dovich effect at high frequencies. The contribution from plasma infall is less important for reasonable velocities. We give a convenient analytical expression for the dependence of the cross-over frequency on temperature, optical depth, and gas infall speed. Optical depth effects are often more important than relativistic corrections, and should be taken into account for high-precision work, but are smaller than the typical kinematic effect from cluster radial velocities.

This dissertation describes the development of a novel gamma-ray imaging system concept and presents results from Monte Carlo simulations of the new design. Current designs for large field-of-view gamma cameras suitable for homeland security applications implement either a coded aperture or a Compton scattering geometry to image a gamma-ray source. Both of these systems require large, expensive position-sensitive detectors in order to work effectively. By combining characteristics of both of these systems, a new design can be implemented that does not require such expensive detectors and that can be scaled down to a portable size. This new system has significant promise in homeland security, astronomy, botany and other fields, while future iterations may prove useful in medical imaging, other biological sciences and other areas, such as non-destructive testing. A proof-of-principle study of the new gamma-ray imaging system has been performed by Monte Carlo simulation. Various reconstruction methods have been explored and compared. General-Purpose Graphics-Processor-Unit (GPGPU) computation has also been incorporated. The resulting code is a primary design tool for exploring variables such as detector spacing, material selection and thickness and pixel geometry. The advancement of the system from a simple 1-dimensional simulation to a full 3-dimensional model is described. Methods of image reconstruction are discussed and results of simulations consisting of both a 4 x 4 and a 16 x 16 object space mesh have been presented. A discussion of the limitations and potential areas of further study is also presented.

In late 1922 Arthur Holly Compton (1892-1962) discovered that an X-ray quantum of radiation undergoes a discrete change in wavelength when it experiences a billiard-ball collision with a single atomic electron, a phenomenon that became known as the Compton effect and for which he shared the Nobel Prize in Physics for 1927. But for more than five years before he made his discovery, Compton had analyzed X-ray scattering in terms of classical electrodynamics. I suggest that his colleague at Washington University in St. Louis, G. E. M. Jauncey (1888-1947), helped materially to persuade him to embrace the quantum interpretation of his X-ray scattering experiments.

In our work, we describe two types of Compton processes. As an example of an inclusive process, we consider the high-energy photoproduction of massive muon pairs off the nucleon. We analyze the process in the framework of the QCD parton model, in which the usual parton distributions emerge as a tool to describe the nucleon in terms of quark and gluonic degrees of freedom. To study its exclusive version, a new class of phenomenological functions is required, namely, generalized parton distributions. They can be considered as a generalization of the usual parton distributions measured in deeply inelastic lepton-nucleon scattering. Generalized parton distributions (GPDs) may be observed in hard exclusive reactions such as deeply virtual Compton scattering. We develop an extension of this particular process into the weak interaction sector. We also investigate a possible application of the GPD formalism to wide-angle real Compton scattering.

Astronomy in the MeV gamma-ray band (0.1 - 100 MeV) holds a rich promise for elucidating many fundamental questions concerning the most violent cosmic phenomena. The next generation of gamma-ray space instrument could be a Compton and pair-creation telescope made of two main parts: a silicon tracker optimized for Compton scattering of cosmic gamma rays and a calorimeter that absorbs the scattered photons. We present here the first results of GAMCOTE, a GAMma-ray COmpton TElescope prototype which includes thick double sided silicon strip detectors coupled to a LaBr3:Ce crystal read by a 64 multi-anode photomultiplier tube.

We present simple and accurate analytical formulas for the rates of Compton scattering by relativistic electrons integrated over the energy distribution of blackbody seed photons. Both anisotropic scattering, in which blackbody photons arriving from one direction are scattered by an anisotropic electron distribution into another direction, and scattering of isotropic seed photons are considered. Compton scattering by relativistic electrons off blackbody photons from either stars or cosmic microwave background takes place, in particular, in microquasars, colliding-wind binaries, supernova remnants, interstellar medium and the vicinity of the Sun.

Isotropic Compton profile of NbB(2) using 20 Ci (137)Cs Compton spectrometer is compared with our theoretical profiles obtained from the density functional theory (DFT) within the first and the second order generalized gradient approximation (GGA) and the hybridization of Hartree-Fock and DFT. A good agreement between GGA based profiles and the experiment validates the applicability of second order GGA in momentum densities. Energy bands, density of states and real space analysis of the experimental profile show metallic character of NbB(2).

Since late 1970s, laser driven Compton gamma-ray beam facilities have been developed, contradicted and operated around the world for basic science research in nuclear physics and astrophysics, and for applied research in the areas of national security and industrial applications. Currently, TUNL's High Intensity Gamma-ray Source (HIGS) located at Duke University campus is the most intense Compton gamma-ray beam facility dedicated for scientific research. Driven by a high power storage ring Free-Electron Laser (FEL), HIGS produces nearly monochromatic, highly polarized gamma-ray beams from 1 to 100 MeV, with its peak performance of total flux up to few 1E10 g/s and a spectral flux of more than 1E3 g/s/eV in the few MeV to 10 MeV region. The next generation Compton gamma-ray sources will be developed using advanced laser technologies. This talk will provide an overview of new Compton gamma-beam projects, including the ELI-NP (Extreme Light Infrastructure - Nuclear Physics) project in Romania and the HIGS upgrade project - HIGS2. Since late 1970s, laser driven Compton gamma-ray beam facilities have been developed, contradicted and operated around the world for basic science research in nuclear physics and astrophysics, and for applied research in the areas of national security and industrial applications. Currently, TUNL's High Intensity Gamma-ray Source (HIGS) located at Duke University campus is the most intense Compton gamma-ray beam facility dedicated for scientific research. Driven by a high power storage ring Free-Electron Laser (FEL), HIGS produces nearly monochromatic, highly polarized gamma-ray beams from 1 to 100 MeV, with its peak performance of total flux up to few 1E10 g/s and a spectral flux of more than 1E3 g/s/eV in the few MeV to 10 MeV region. The next generation Compton gamma-ray sources will be developed using advanced laser technologies. This talk will provide an overview of new Compton gamma-beam projects, including the ELI-NP (Extreme Light

Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factorsmore » $$H_{Im}$$ and $$\\tilde{H}_{Im}$$ with uncertainties, in average, of the order of 30%.« less

We present advances with a 32 element scalable, segmented dual mode imager. Scaling up the number of cells results in a 1.4 increase in efficiency over a system we deployed last year. Variable plane separation has been incorporated which further improves the efficiency of the detector. By using 20 cm diameter cells we demonstrate that we could increase sensitivity by a factor of 6. We further demonstrate gamma ray imaging in from Compton scattering. This feature allows for powerful dual mode imaging. Selected results are presented that demonstrate these new capabilities.

We present advances with a 32 element scalable, segmented dual mode imager. Scaling up the number of cells results in a 1.4 increase in efficiency over a system we deployed last year. Variable plane separation has been incorporated which further improves the efficiency of the detector. By using 20 cm diameter cells we demonstrate that we could increase sensitivity by a factor of 6. We further demonstrate gamma ray imaging in from Compton scattering. This feature allows for powerful dual mode imaging. Selected results are presented that demonstrate these new capabilities.

A wastewater treatment system employing a UASB reactor in temperate regions requires biogas as a heat source for the UASB reactor during low temperature seasons. In this case, removal of H2S in the biogas by means of a scrubber before burning is necessary in order to prevent the boilers from corroding. Heating of the UASB reactor is, however, unnecessary in a warm season, and the scrubber and biogas become useless. Methane-dependent water quality improvement using the scrubber and biogas would be one way to use them efficiently during the warm season. The possible dual-purpose use of a packed-bed reactor was examined, with one of its uses being the scrubbing of biogas during the cold season and the other being the methane-dependent improvement of effluent water quality during the warm season. A bench scale packed-bed filled with plastic latticed-ring media was installed in a livestock wastewater treatment plant consisting of a UASB reactor and a trickling filter for post-treatment. The packed-bed was operated with biogas flowing at a superficial velocity of 0.14-0.39 m h(-1) and the hydraulic loading of trickling filter effluent sprayed onto the media 9.4-26.1 m3 m2 day(-1). H2S in the biogas from the UASB reactor was reduced from 1,200-2,500 ppm to less than 2 ppm by the reactor. Methane-dependent water quality improvement was examined using a laboratory scale reactor to which methane and/or air was supplied from the bottom, while plant effluent was spread from the top of the reactor. When the mixture gas of methane and air (volume ratio 1:3) was added to the reactor, biofilm grew on the surface of the media. Accompanying this growth, ammonium and phosphate in the spread water decreased, probably due to assimilation by the methane-oxidizing bacteria. Though assimilation activity dropped after the accumulation of biomass, it could be reactivated by washing out the excess biomass. Periodical backwash at a rate of more than once a week seemed to efficiently maintain

We present new Nuclear Spectroscopic Telescope Array (NuSTAR ) and Chandra observations of NGC 3393, a galaxy reported to host the smallest separation dual active galactic nuclei (AGN) resolved in the X-rays. While past results suggested a 150 pc separation dual AGN, three times deeper Chandra imaging, combined with adaptive optics and radio imaging suggest a single, heavily obscured, radio-bright AGN. Using Very Large Array and Very Long Baseline Array data, we find an AGN with a two-sided jet rather than a dual AGN and that the hard X-ray, UV, optical, near-infrared, and radio emission are all from a single point source with a radius <0 .″ 2. We find that the previously reported dual AGN is most likely a spurious detection resulting from the low number of X-ray counts (<160) at 6-7 keV and Gaussian smoothing of the data on scales much smaller than the point-spread function (PSF) (0 .″ 25 versus 0 .″ 80 FWHM). We show that statistical noise in a single Chandra PSF generates spurious dual peaks of the same separation (0 .″ 55±0 .″ 07 versus 0 .″ 6) and flux ratio (39% ± 9% versus 32% counts) as the purported dual AGN. With NuSTAR, we measure a Compton-thick source ({N}{{H}}=2.2+/- 0.4× {10}24 {{cm}}-2) with a large torus half-opening angle, {θ }{tor}={79}-19+1^\\circ which we postulate results from feedback from strong radio jets. This AGN shows a 2-10 keV intrinsic-to-observed flux ratio of ≈ 150 ({L}2-10\\{keV\\{int}}=2.6+/- 0.3× {10}43 {erg} {{{s}}}-1 versus {L}2-10\\{keV\\{observed}}=1.7+/- 0.2× {10}41 {erg} {{{s}}}-1). Using simulations, we find that even the deepest Chandra observations would severely underestimate the intrinsic luminosity of NGC 3393 above z\\gt 0.2, but would detect an unobscured AGN of this luminosity out to high redshift (z≈ 5).

New data points for unpolarized Deeply Virtual Compton Scattering cross sections have been extracted from the E00-110 experiment at Q2=1.9 GeV2 effectively doubling the statistics available in the valence region. A careful study of systematic uncertainties has been performed.

We have developed a new Comptonization model to propose, for the first time, a self consistent physical interpretation of the complex spectral evolution seen in NS LMXBs. The model and its application to LMXBs are presented and compared to the Simbol-X expected capabilities.

Here, we report on a measurement of the constancy and anisotropy of the speed of light relative to the electrons in photon-electron scattering. We also used the Compton scattering asymmetry measured by the new Compton polarimeter in Hall~C at Jefferson Lab to test for deviations from unity of the vacuum refractive index ($n$). For photon energies in the range of 9 - 46 MeV, we obtain a new limit of $1-n < 1.4 \\times 10^{-8}$. In addition, the absence of sidereal variation over the six month period of the measurement constrains any anisotropies in the speed of light. These constitute the first study of Lorentz invariance using Compton asymmetry. Within the minimal standard model extension framework, our result yield limits on the photon and electron coefficients $\\tilde{\\kappa}_{0^+}^{YZ}, c_{TX}, \\tilde{\\kappa}_{0^+}^{ZX}$, and $c_{TY}$. Though, these limits are several orders of magnitude larger than the current best limits, they demonstrate the feasibility of using Compton asymmetry for tests of Lorentz invariance. For future parity violating electron scattering experiments at Jefferson Lab we will use higher energy electrons enabling better constraints.

In 1913, when American physicist Arthur Compton was an undergraduate, he invented a simple way to measure the rotation rate of the Earth with a tabletop-sized experiment. The experiment consisted of a large diameter circular ring of thin glass tubing filled with water and oil droplets. After placing the ring in a plane perpendicular to the surface of the Earth and allowing the fluid mixture of oil and water to come to rest, he then abruptly rotated the ring, flipping it 180 degrees about an axis passing through its own plane. The result of the experiment was that the water acquired a measurable drift velocity due to the Coriolis effect arising from the daily rotation of the Earth about its own axis. Compton measured this induced drift velocity by observing the motion of the oil droplets in the water with a microscope. This device, which is now named after him, is known as a Compton generator. The fundamental research objective of this project is to explore the dynamics of a quantum-mechanical analogue to the classical Compton generator experiment through the use of numerical simulations. We present our preliminary results on this system and the future direction of the project. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575.

Here, we report on a measurement of the constancy and anisotropy of the speed of light relative to the electrons in photon-electron scattering. We also used the Compton scattering asymmetry measured by the new Compton polarimeter in Hall~C at Jefferson Lab to test for deviations from unity of the vacuum refractive index (more » $n$). For photon energies in the range of 9 - 46 MeV, we obtain a new limit of $$1-n < 1.4 \\times 10^{-8}$$. In addition, the absence of sidereal variation over the six month period of the measurement constrains any anisotropies in the speed of light. These constitute the first study of Lorentz invariance using Compton asymmetry. Within the minimal standard model extension framework, our result yield limits on the photon and electron coefficients $$\\tilde{\\kappa}_{0^+}^{YZ}, c_{TX}, \\tilde{\\kappa}_{0^+}^{ZX}$$, and $$c_{TY}$$. Though, these limits are several orders of magnitude larger than the current best limits, they demonstrate the feasibility of using Compton asymmetry for tests of Lorentz invariance. For future parity violating electron scattering experiments at Jefferson Lab we will use higher energy electrons enabling better constraints.« less

Recent results of experiments performed with two different Compton-suppressed detectors arrays in Daresbury and Berkeley (/sup 163,164/Yb and /sup 154/Er, respectively), are presented together with a brief description of the national French array presently under construction in Strasbourg. 25 refs., 15 figs.

Synchrotron radiation produced as an electron beam passes through a bending magnet is a significant source of background in many experiments. Using modeling, we show that simple modifications of the magnet geometry can reduce this background by orders of magnitude in some circumstances. Specifically, we examine possible modifications of the four dipole magnets used in Jefferson Lab's Hall A Compton polarimeter chicane. This Compton polarimeter has been a crucial part of experiments with polarized beams and the next generation of experiments will utilize increased beam energies, up to 11 GeV, requiring a corresponding increase in Compton dipole field to 1.5 T. In consequence, the synchrotron radiation (SR) from the dipole chicane will be greatly increased. Three possible modifications of the chicane dipoles are studied; each design moves about 2% of the integrated bending field to provide a gentle bend in critical regions along the beam trajectory which, in turn, greatly reduces the synchrotron radiation within the acceptance of the Compton polarimeter photon detector. Each of the modifications studied also softens the SR energy spectrum at the detector sufficiently to allow shielding with 5 mm of lead. Simulations show that these designs are each capable of reducing the background signal due to SR by three orders of magnitude. The three designs considered vary in their need for vacuum vessel changes and in their effectiveness.

Two inverse-Compton disk models for the hard X-ray spectra of quasi-stellar objects and active galactic nuclei are studied and compared. One is a slightly generalized version of the Shapiro, Lightman and Eardley optically thin disk model, and the other is a conduction-stabilized Corona model. Observational distinctions between the two models are discussed.

This article describes a new approach to radiation theory. This theory, expounded by Lieu and Axford, uses the concept of inverse Compton scattering to explain with unprecedented simplicity all the classical and quantum electrodynamic properties of synchrotron radiation, unifying two fundamental processes in physics. Ramifications of this theory are also discussed. 13 refs., 1 fig.

In a usual modern physics class the Compton effect is used as the pedagogical model for introducing relativity into quantum effects. The shift in photon wavelengths is usually introduced and derived using special relativity. Indeed, this works well for explaining the effect. However, in the senior author's class one of the student coauthors…

A campus climate survey was conducted at Compton Community College in California to assess students' attitudes towards departments, staff, and their experiences at the college. Questionnaires were administered in-class to 6% (n=308) of the study body. The 91-item questionnaire covered academic advising and counseling effectiveness; academic…

We report on a measurement of the constancy and anisotropy of the speed of light relative to the electrons in photon-electron scattering. We used the Compton scattering asymmetry measured by the new Compton polarimeter in Hall C at Jefferson Lab (JLab) to test for deviations from unity of the vacuum refractive index (n). For photon energies in the range of 9-46 MeV, we obtain a new limit of 1 - n < 1.4 × 10-8. In addition, the absence of sidereal variation over the six-month period of the measurement constrains any anisotropies in the speed of light. These constitute the first study of Lorentz invariance (LI) using Compton asymmetry. Within the minimal Standard Model extension (MSME) framework, our result yield limits on the photon and electron coefficients κ˜0+Y Z, cTX, κ˜0+ZX and cTY. Although these limits are several orders of magnitude larger than the current best limits, they demonstrate the feasibility of using Compton asymmetry for tests of LI. Future parity-violating electron-scattering experiments at JLab will use higher energy electrons enabling better constraints.

In this study, we explore both inverse Compton and Compton scattering processes using the Chang and Cooper scheme to form a deterministic solution of the Kompaneets equation. We examine the individual terms of the Kompaneets equation and illustrate their effect on the equilibrium solution. We use two examples (a Gaussian line profile and a Planck profile) to illustrate the advective and diffusive properties of the Kompaneets operator. We also explore both inverse Compton scattering and Compton scattering, and discuss and illustrate the Bose-Einstein condensation feature of the Compton scattering spectrum.

The "Compton-Hall" voltmeter is a radiation-based voltage diagnostic that has been developed to measure voltages on high-power (TW) pulsed generators. The instrument collimates photons generated from bremsstrahlung produced in the diode onto an aluminum target to generate Compton-generated electrons. Permanent magnets bend the Compton electron orbits that escape the target toward a silicon pin diode detector. A GaAs photoconductive detector (PCD) detects photons that pass through the Compton target. The diode voltage is determined from the ratio of the electron dose in the pin detector to the x-ray dose in the PCD. The Integrated Tiger Series of electron-photon transport codes is used to determine the relationship between the measured dose ratio and the diode voltage. Variations in the electron beam's angle of incidence on the bremsstrahlung target produce changes in the shape of the photon spectrum that lead to large variations in the voltage inferred from the voltmeter. The voltage uncertainty is minimized when the voltmeter is fielded at an angle of 45° with respect to the bremsstrahlung target. In this position, the photon spectra for different angles of incidence all converge onto a single spectrum reducing the uncertainty in the voltage to less than 10% for voltages below 4 MV. Higher and lower voltages than the range considered in this article can be measured by adjusting the strength of the applied magnetic field or the position of the electron detector relative to the Compton target. The instrument was fielded on the Gamble II pulsed-power generator configured with a plasma opening switch. Measurements produced a time-dependent voltage with a peak (3.7 MV) that agrees with nuclear activation measurements and a pulse shape that is consistent with the measured radiation pulse shape.

Compton scattering from protons and neutrons provides important insight into the structure of the nucleon. A new extraction of the static electric and magnetic dipole polarisabilities αE 1 and βM 1 of the proton and neutron from all published elastic data below 300 MeV in Chiral Effective Field Theory shows that within the statistics-dominated errors, the proton and neutron polarisabilities are identical, i.e. no iso-spin breaking effects of the pion cloud are seen. Particular attention is paid to the precision and accuracy of each data set, and to an estimate of residual theoretical uncertainties. ChiEFT is ideal for that purpose since it provides a model-independent estimate of higher-order corrections and encodes the correct low-energy dynamics of QCD, including, for few-nucleon systems used to extract neutron polarisabilities, consistent nuclear currents, rescattering effects and wave functions. It therefore automatically respects the low-energy theorems for photon-nucleus scattering. The Δ (1232) as active degree of freedom is essential to realise the full power of the world's Compton data.Its parameters are constrained in the resonance region. A brief outlook is provided on what kind of future experiments can improve the database. Supported in part by UK STFC, DOE, NSF, and the Sino-German CRC 110.

Background: Parity-violating elastic electron-nucleon scattering at low momentum transfer allows one to access the nucleon's weak charge, the vector coupling of the Z -boson to the nucleon. In the Standard Model and at tree level, the weak charge of the proton is related to the weak mixing angle and accidentally suppressed, QWp ,tree=1 -4 sin2θW≈0.07 . Modern experiments aim at extracting QWp at ˜1 % accuracy. Similarly, parity nonconservation in atoms allows to access the weak charge of atomic nuclei. Purpose: We consider a novel class of radiative corrections due to the exchange of two photons, with parity violation in the hadronic/nuclear system. These corrections are prone to long-range interactions and may affect the extraction of sin2θW from the experimental data at the relevant level of precision. Methods: The two-photon exchange contribution to the parity-violating electron-proton scattering amplitude is studied in the framework of forward dispersion relations. We address the general properties of the parity-violating forward Compton scattering amplitude and use relativistic chiral perturbation theory to provide the first field-theoretical proof that it obeys a superconvergence relation. Results: We show that the significance of this new correction increases with the beam energy in parity-violating electron scattering, but the superconvergence relation protects the formal definition of the weak charge as a limit at zero-momentum transfer and zero energy. We evaluate the new correction in a hadronic model with pion loops and the Δ (1232 ) resonance, supplemented with a high-energy contribution. For the kinematic conditions of existing and upcoming experiments we show that two-photon exchange corrections with hadronic or nuclear parity violation do not pose a problem for the interpretation of the data in terms of the weak mixing angle at the present level of accuracy. Conclusions: Two-photon exchange in presence of hadronic or nuclear parity violation

The purpose of this study is to compare and evaluate the performance of a multiple-scattering Compton imager (MSCI) to measure prompt gamma-rays emitted during proton therapy. Because prompt gamma-rays are generated simultaneously during the proton beam delivery, the falloff position of the Bragg peak of the proton beam can be determined from the distribution of prompt gamma-rays. The detection system was designed using three CdZnTe detector layers that can track radiation of unknown energy on the basis of effective Compton scattering events. The simple back-projection, filtered back-projection, and maximum likelihood expectation maximization (MLEM) algorithms were applied for the reconstructed Compton images. The falloff positions of the Bragg peaks determined from individual MSCIs were compared with the theoretical values calculated using the Monte Carlo N-Particle eXtended code. Moreover, the performance of the MSCI was compared with that of a previously developed system based on a slit collimator gamma camera. In summary, the MSCI with the MLEM reconstruction algorithm was better than the other reconstruction methods in terms of the falloff position of the Bragg peak, the angular resolution, and the signal-to-noise ratio.

This award pertains to an RXTE observation of the Seyfert 1 galaxy Akn 120. The purpose of the observation was to measure the Fe-K emission line and the Compton reflection continuum with RXTE, simultaneously with Chandra and XMM. Such measurements can severely constrain accretion disk models of the central engine since the Fe-K line emission and Compton reflection are intimately related in terms of the physics of X-ray reprocessing in optically-thick matter. Akn 120 was selected for this study because it is amongst the brightest AGN in its class and has a particularly strong and apparently broad Fe-K emission line. The results could then also be used to lay the ground work for even higher resolution studies with Astro-E2. Unfortunately, the Chandra observation was not performed but a contemporaneous XMM observation was performed by another group of researchers. Those data recently became public and can be compared with the RXTE data. In addition, non-contemporaneous observations with other missions do still provide additional important constraints (for example any non-varying line or continuum emission components can be established and used to reject or preserve various model scenarios). We analyzed the RXTE data and found a strong Fe-K emission line (resolved even with the poor resolution of RXTE), and a strong Compton-reflection continuum (see Fig. l(a)). We found that the results of archival ASCA data on Akn 120 had not been published in the literature so we analyzed the ASCA data too, in order to compare with the new RXTE data. Fig. l(b) shows that the ASCA data also reveal a strong, broad FeK emission line (but the data are not sensitive to the Compton-reflection continuum). We compared our spectral fitting results for the RXTE and ASCA data with the results from XMM and from previous RXTE observations.

Compton Cameras emerged as an alternative for real-time dose monitoring techniques for Particle Therapy (PT), based on the detection of prompt-gammas. As a consequence of the Compton scattering process, the gamma origin point can be restricted onto the surface of a cone (Compton cone). Through image reconstruction techniques, the distribution of the gamma emitters can be estimated, using cone-surfaces backprojections of the Compton cones through the image space, along with more sophisticated statistical methods to improve the image quality. To calculate the Compton cone required for image reconstruction, either two interactions, the last being photoelectric absorption, or three scatter interactions are needed. Because of the high energy of the photons in PT the first option might not be adequate, as the photon is not absorbed in general. However, the second option is less efficient. That is the reason to resort to spectral reconstructions, where the incoming γ energy is considered as a variable in the reconstruction inverse problem. Jointly with prompt gamma, secondary neutrons and scattered photons, not strongly correlated with the dose map, can also reach the imaging detector and produce false events. These events deteriorate the image quality. Also, high intensity beams can produce particle accumulation in the camera, which lead to an increase of random coincidences, meaning events which gather measurements from different incoming particles. The noise scenario is expected to be different if double or triple events are used, and consequently, the reconstructed images can be affected differently by spurious data. The aim of the present work is to study the effect of false events in the reconstructed image, evaluating their impact in the determination of the beam particle ranges. A simulation study that includes misidentified events (neutrons and random coincidences) in the final image of a Compton Telescope for PT monitoring is presented. The complete chain of

An important diagnostic tool for inertial confinement fusion will be time-resolved radiographic imaging of the dense cold fuel surrounding the hot spot. The measurement technique is based on point-projection radiography at photon energies from 60 to 200 keV where the Compton effect is the dominant contributor to the opacity of the fuel or pusher. We have successfully applied this novel Compton radiography technique to the study of the final compression of directly driven plastic capsules at the OMEGA facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The radiographs have a spatial and temporal resolution of {approx}10 {mu}m and {approx}10 ps, respectively. A statistical accuracy of {approx}0.5% in transmission per resolution element is achieved, allowing localized measurements of areal mass densities to 7% accuracy. The experimental results show 3D nonuniformities and lower than 1D expected areal densities attributed to drive asymmetries and hydroinstabilities.

According to leptonic models for the high-energy emission from blazars, relativistic electrons in the inner jets inverse-Compton scatter photons from a variety of sources. Seed photons are certainly introduced via the synchrotron process from the electrons themselves, but external sources of seed photons may also be present. In this paper, we present detailed derivations of the equations describing external inverse-Compton scattering from two sources of seed photons: direct emission from the accretion disk, and accretion disk photons that have scattered off the broad line region. For each source, we derive the seed photon spectrum incident on the jet, the single electron energy loss rate, and the emitted photon spectrum.

In recent years, observations of the Iron K alpha reverberation in supermassive black holes have provided a new way to probe the inner accretion flow. Furthermore, a time lag between the direct coronal emission and the reprocessed emission forming the Compton Hump in AGN has been observed. In order to model this Compton Hump reverberation we performed general relativistic ray tracing studies of the accretion disk surrounding supermassive black holes, taking into account both the radial and angular dependence of the ionization parameter. We are able to model emission not only from a lamp-post corona but also implementing 3D corona geometries. Using these results we are able to model the observed data to gain additional insight into the geometry of the corona and the structure of the inner accretion disk.

In this work we analyze the wave-particle aspects of radiation in (incoherent) Compton scattering in the radiation energy range from 2-100 keV. From the calculated cross sections of the scattering from the electron (positron), hydrogen and positronium we construct the interpretation functions (IFs), where our assertion is that the Compton scattering from the free electron (positron) is an established example of the particle behavior of radiation. These IFs estimate the possibility of the interpretation of radiation in terms of waves or particles in an analogy with the analysis carried out in the coherent scattering of light. Based on these IFs we propose a new criterion for the estimation of the validity of the impulse approximation (IA).

Recent progress in accelerator physics and laser technology have enabled the development of a new class of gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development at LLNL. High-brightness, relativistic electron bunches produced by the linac interact with a Joule-class, 10 ps laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented.

Compton gamma rays with energies 1 MeV largely results from scattering between electrons, with energies 100 MeV, and photons in the optical and infrared range and the 2.7 K universal blackbody radiation. An empirical model of the inverse Compton (IC) gamma ray production in the Galaxy is presented, using the most recent estimate of the interstellar electron spectrum given by Webber and a combination of optical and infrared observations to determine the galactic distribution of the various components of the interstellar photon field. The present analysis has an improved precision since the spectral distribution of the IC source function as well as that of the interstellar photon field are more accurately taken into account. The exact evaluation of the IC process is applied and different electron distribution models are considered.

The first ever Compton profile study of polycrystalline ZnBr{sub 2} is presented in this paper. The measurement of polycrystalline sample of ZnBr{sub 2} is performed using 59.54 keV gamma-rays emanating from an {sup 241}Am radioisotope. Theoretical calculations are performed following the Ionic model calculations for a number of configurations Zn{sup +x}Br{sub 2}{sup -x/2}(0.0{<=}x{<=}2.0 in step of 0.5) utilizing free atom profiles. The ionic model suggest transfer of 2.0 electrons from 4 s state of Zn to 4 p state of two Br atoms. The autocorrelation function B(z) is also derived from experiment and the most favoured ionic valence Compton profiles.

Nonlinear effects are known to occur in Compton scattering light sources, when the laser normalized 4-potential, A = e{radical}-A{sub {mu}}A{sup {mu}}/m{sub 0}c approaches unity. In this letter, it is shown that nonlinear spectral features can appear at arbitrarily low values of A, if the fractional bandwidth of the laser pulse, {Delta}{phi}{sup -1}, is sufficiently small to satisfy A{sup 2} {Delta}{phi} {approx_equal} 1. A three dimensional analysis, based on a local plane-wave, slow-varying envelope approximation, enables the study of these effects for realistic interactions between an electron beam and a laser pulse, and their influence on high-precision Compton scattering light sources.

Compton scattered x-rays can be generated using a configuration consisting of a single ultrashort laser pulse and a shaped gas target. Upon ionization the gas target serves as a plasma mirror that reflects the incident pulse providing a counter-propagating electromagnetic wiggler. While plasma mirrors are often conceived as linear Fresnel reflectors, we demonstrate that for high-intensity, ultrashort laser pulses the reflection results from two distinct nonlinear mechanisms. At lower densities, the reflection arises from the emission of an electromagnetic pulse during the saturation of the absolute Raman instability at the quarter critical surface. At higher densities the reflection of the pulse from the critical surface sets up a density fluctuation that acts as a Bragg-like reflector. These mechanisms, occurring in a non-perturbative regime of laser-plasma interactions, are examined numerically in order to characterize the Compton scattered radiation.

An important diagnostic tool for inertial confinement fusion will be time-resolved radiographic imaging of the dense cold fuel surrounding the hot spot. The measurement technique is based on point-projection radiography at photon energies from 60-200 keV where the Compton effect is the dominant contributor to the opacity of the fuel or pusher. We have successfully applied this novel Compton Radiography technique to the study of the final compression of directly driven plastic capsules at the OMEGA facility. The radiographs have a spatial and temporal resolution of {approx}10 {micro}m and {approx}10ps, respectively. A statistical accuracy of {approx}0.5% in transmission per resolution element is achieved, allowing localized measurements of areal mass densities to 7% accuracy. The experimental results show 3D non-uniformities and lower than 1D expected areal densities attributed to drive asymmetries and hydroinstabilities.

The Qweak experiment at Jefferson Lab aims to make a 4% measurement of the parity-violating asymmetry in elastic scattering at very low Q{sup 2} of a longitudinally polarized electron beam off a proton target. One of the dominant experimental systematic uncertainties in Qweak will result from determining the beam polarization. A new Compton polarimeter was installed in the fall of 2010 to provide a non-invasive and continuous monitoring of the electron beam polarization in Hall C at Jefferson Lab. The Compton-scattered electrons are detected in four planes of diamond micro-strip detectors. We have achieved the design goals of <1% statistical uncertainty per hour and expect to achieve <1% systematic uncertainty.

A system in one embodiment includes an array of radiation detectors; and an array of imagers positioned behind the array of detectors relative to an expected trajectory of incoming radiation. A method in another embodiment includes detecting incoming radiation with an array of radiation detectors; detecting the incoming radiation with an array of imagers positioned behind the array of detectors relative to a trajectory of the incoming radiation; and performing at least one of Compton imaging using at least the imagers and coded aperture imaging using at least the imagers. A method in yet another embodiment includes detecting incoming radiation with an array of imagers positioned behind an array of detectors relative to a trajectory of the incoming radiation; and performing Compton imaging using at least the imagers.

In this paper, we show that there is a Non-Commutative Plane (NCP) in the perpendicular magnetic fields in the accelerator, and the QED with NCP (QED-NCP) has been formulated. Being similar to the theory of quantum Hall effects, an effective filling factor f(B) is introduced, which characters the possibility occupied the LLL state by the electrons living on NCP. The back Compton scattering amplitudes of QED-NCP are derived, and the differential cross sections for the process with fixed initial polarizing electrons and photons are calculated. We propose to precisely measure the polarization dependent differential cross sections of the back Compton scattering in the perpendicular magnetic fields experimentally, which may lead to reveal the effects of QED with NCP. This should be interesting and remarkable. The existing Spring-8's data have been analyzed primitively, and some hints for QED-NCP effects are seen.

The state-of-the-art X-ray source based on inverse-Compton scattering between a high-brightness, relativistic electron beam produced by an X-band RF accelerator and a high-intensity laser pulse generated by chirped-pulse amplification (CPA) has been carried out by our research team at Lawrence Livermore National Laboratory. This system is called "Compact Laser-Compton X-ray Source". The applications include nuclear resonance fluorescence, medical imaging and therapy, and nuclear waste imaging and assay. One of the key factors in this system is how we know the interaction happened in the vacuum chamber, which is the spectrometer of electron beams. The other key factor is the interaction after the spectrometer, which is the outgoing X-ray. In this thesis, the work in the simulation for the result of the interaction between electrons and the laser, the calibration of spectrometer, and laser focus characterization are discussed.

A mobile instrument has been developed for the detection and mapping of detachments in frescos by using Compton back scattered photons. The instrument is mainly composed of a high energy X-ray tube, an X-ray detection system and a translation table. The instrument was first applied to samples simulating various detachment situations, and then transferred to the Vatican Museum to detect detachments and inhomogeneities in the stanza di Eliodoro, one of the "Raphael's stanze".

This paper describes the Monte Carlo simulation developed specifically for the Virtual Compton Scattering (VCS) experiments below pion threshold that have been performed at MAMI and JLab. This simulation generates events according to the (Bethe-Heitler + Born) cross-section behaviour and takes into account all relevant resolution-deteriorating effects. It determines the "effective" solid angle for the various experimental settings which are used for the precise determination of the photon electroproduction absolute cross-section.

Washington DC 20024 ABSTRACT A primary objective of the Compton Observatory is the direct study of explo- sive nucleosynthesis in supernovae and classical...our best chance to detect -rays from 22Na, a unique nucleosynthesis byproduct of the explosive hydrogen burning thought to power classical novae. The...radio, x-ray), or might go into PdV work. As for the last two e ects in the list, we doubt, based on straightforward nucleosynthesis arguments,9 that

The Compton wavelength gives the minimum radius within which the mass of a particle may be localized due to quantum effects, while the Schwarzschild radius gives the maximum radius within which the mass of a black hole may be localized due to classial gravity. In a mass-radius diagram, the two lines intersect near the Planck point ( l P , m P ), where quantum gravity effects become significant. Since canonical (non-gravitational) quantum mechanics is based on the concept of wave-particle duality, encapsulated in the de Broglie relations, these relations should break down near ( l P , m P ). It is unclear what physical interpretation can be given to quantum particles with energy E ≫ m P c 2, since they correspond to wavelengths λ ≪ l P or time periods τ ≪ t P in the standard theory. We therefore propose a correction to the standard de Broglie relations, which gives rise to a modified Schrödinger equation and a modified expression for the Compton wavelength, which may be extended into the region E ≫ m P c 2. For the proposed modification, we recover the expression for the Schwarzschild radius for E ≫ m P c 2 and the usual Compton formula for E ≪ m P c 2. The sign of the inequality obtained from the uncertainty principle reverses at m ≈ m P , so that the Compton wavelength and event horizon size may be interpreted as minimum and maximum radii, respectively. We interpret the additional terms in the modified de Broglie relations as representing the self-gravitation of the wave packet.

The density of the lung of a patient suffering from pulmonary edema is monitored by irradiating the lung by a single collimated beam of monochromatic photons and measuring the energies of photons Compton backscattered from the lung by a single high-resolution, high-purity germanium detector. A compact system geometry and a unique data extraction scheme are utilized to monimize systematic errors due to the presence of the chestwall and multiple scattering.

The density of the lung of a patient suffering from pulmonary edema is monitored by irradiating the lung by a single collimated beam of monochromatic photons and measuring the energies of photons compton back-scattered from the lung by a single high-resolution, high-purity germanium detector. A compact system geometry and a unique data extraction scheme are utilized to minimize systematic errors due to the presence of the chestwall and multiple scattering. 11 figs., 1 tab.

We propose detailed tests of the handbag approximation in exclusive deeply virtual Compton scattering. Those tests make no use of any prejudice about parton correlations in the proton which are basically unknown objects and beyond the scope of perturbative QCD. Since important information on the proton substructure can be gained in the regime of light cone dominance we consider that such a class of tests is of special relevance.

We propose detailed tests of the handbag approximation in exclusive deeply virtual Compton scattering. Those tests make no use of any prejudice about parton correlations in the proton which are basically unknown objects and beyond the scope of perturbative QCD. Since important information on the proton substructure can be gained in the regime of light cone dominance we consider that such a class of tests is of special relevance. {copyright} {ital 1998 American Institute of Physics.}

A hodoscope calorimeter comprising of 704 lead-glass blocks is described. The calorimeter was constructed for use in the JLab Real Compton Scattering experiment. The detector provides a measurement of the coordinates and the energy of scattered photons in the GeV energy range with resolutions of 5 mm and 6\\%/$\\sqrt{E_\\gamma \\, [GeV]}$, respectively. Design features and performance parameters during the experiment are presented.

Current conservation is a vital condition in electrodynamics. We review the literature concerning the ways to ensure that the formalism used in calculating amplitudes for the scattering of charged particles is in compliance with current conservation. For the case of electron scattering off a scalar and a spin-1/2 target as well as Compton scattering on a scalar target, we present some novelties besides reviewing the literature.

A compact Compton camera with a 4π field of view (FOV) was manufactured using the design parameters optimized with the effective choice of gamma-ray interaction order determined from a Monte Carlo simulation. The camera consisted of six CsI(Na) planar scintillators with a pixelized structure that was coupled to position sensitive photomultiplier tubes (H8500) consisting of multiple anodes connected to custom-made circuits. The size of the scintillator and each pixel was 4.4×4.4×0.5 and 0.2×0.2×0.5 cm, respectively. The total size of each detection module was only 5×5×6 cm and the distance between the detector modules was approximately 10 cm to maximize the camera performance, as calculated by the simulation. Therefore, the camera is quite portable for examining nuclear materials in areas, such as harbors or nuclear power plants. The non-uniformity of the multi-anode PMTs was corrected using a novel readout circuit. Amplitude information of the signals from the electronics attached to the scintillator-coupled multi-anode PMTs was collected using a data acquisition board (cDAQ-9178), and the timing information was sent to a FPGA (SPARTAN3E). The FPGA picked the rising edges of the timing signals, and compared the edges of the signals from six detection modules to select the coincident signal from a Compton pair only. The output of the FPGA triggered the DAQ board to send the effective Compton events to a computer. The Compton image was reconstructed, and the performance of the 4π FOV Compact camera was examined.

A lead-glass hodoscope calorimeter that was constructed for use in the Jefferson Lab Real Compton Scattering experiment is described. The detector provides a measurement of the coordinates and the energy of scattered photons in the GeV energy range with resolutions of 5 mm and 6%/ √{Eγ GeV}. Features of both the detector design and its performance in the high luminosity environment during the experiment are presented.

Rosseland mean opacity plays an important role in theories of stellar evolution and X-ray burst models. In the high-temperature regime, when most of the gas is completely ionized, the opacity is dominated by Compton scattering. Our aim here is to critically evaluate previous works on this subject and to compute the exact Rosseland mean opacity for Compton scattering over a broad range of temperature and electron degeneracy parameter. We use relativistic kinetic equations for Compton scattering and compute the photon mean free path as a function of photon energy by solving the corresponding integral equation in the diffusion limit. As a byproduct we also demonstrate the way to compute photon redistribution functions in the case of degenerate electrons. We then compute the Rosseland mean opacity as a function of temperature and electron degeneracy and present useful approximate expressions. We compare our results to previous calculations and find a significant difference in the low-temperature regime and strong degeneracy. We then proceed to compute the flux mean opacity in both free-streaming and diffusion approximations, and show that the latter is nearly identical to the Rosseland mean opacity. We also provide a simple way to account for the true absorption in evaluating the Rosseland and flux mean opacities.

We calculate Compton scattering off an elementary spin (3/2) particle in a recently proposed framework for the description of high spin fields based on the projection onto eigensubspaces of the Casimir operators of the Poincare group. We also calculate this process in the conventional Rarita-Schwinger formalism. Both formalisms yield the correct Thomson limit but the predictions for the angular distribution and total cross section differ beyond this point. We point out that the average squared amplitudes in the forward direction for Compton scattering off targets with spin s=0, (1/2), 1 are energy independent and have the common value 4e{sup 4}. As a consequence, in the rest frame of the particle the differential cross section for Compton scattering in the forward direction is energy independent and coincides with the classical squared radius. We show that these properties are also satisfied by a spin (3/2) target in the Poincare projector formalism but not by the Rarita-Schwinger spin (3/2) particle.

The Compton camera is a viable and convenient tool used to visualize the distribution of radioactive isotopes that emit gamma rays. After the nuclear disaster in Fukushima in 2011, there is a particularly urgent need to develop "gamma cameras", which can visualize the distribution of such radioisotopes. In response, we propose a portable Compton camera, which comprises 3-D position-sensitive GAGG scintillators coupled with thin monolithic MPPC arrays. The pulse-height ratio of two MPPC-arrays allocated at both ends of the scintillator block determines the depth of interaction (DOI), which dramatically improves the position resolution of the scintillation detectors. We report on the detailed optimization of the detector design, based on Geant4 simulation. The results indicate that detection efficiency reaches up to 0.54%, or more than 10 times that of other cameras being tested in Fukushima, along with a moderate angular resolution of 8.1° (FWHM). By applying the triangular surveying method, we also propose a new concept for the stereo measurement of gamma rays by using two Compton cameras, thus enabling the 3-D positional measurement of radioactive isotopes for the first time. From one point source simulation data, we ensured that the source position and the distance to the same could be determined typically to within 2 meters' accuracy and we also confirmed that more than two sources are clearly separated by the event selection from two point sources of simulation data.

The scaling of laser-Compton X-ray and gamma-ray sources is dependent upon high-current, low-emittance accelerator operation and implementation of efficient laser-electron interaction architectures. Laser-Compton X-rays have been produced using the unique compact X-band linear accelerator at LLNL operated in a novel multibunch mode, and results agree extremely well with modeling predictions. An Andor X-ray CCD camera and image plates have been calibrated and used to characterize the 30 keV laser-Compton X-ray beam. The X-ray source size and the effect of scintillator blur have been measured. K-edge absorption measurements using thin metallic foils confirm the production of narrow energy spread X-rays and results validate X-ray image simulations. Future plans for medically relevant imaging will be discussed with facility upgrades to enable 250 keV X-ray production. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

A new Compton polarimeter was installed in Hall C at Jefferson Lab and used during the Qweak experiment which aims to measure the weak charge of proton with a precision of 4.1%. In this polarimeter the electron beam collides with green laser light stored in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in a lead tungstate crystal. We extract the beam polarization by fitting the experimental asymmetry for each detector strip to the corresponding asymmetry calculated in QED. During the experiment, we took data to cross-calibrate Moller and Compton polarimeters in Hall C. We will share our preliminary conclusions from this comparison. In this talk, we will also present the results from Monte Carlo studies performed to estimate the systematic uncertainties of the polarization measurement along with comparing results from two independent extraction of the polarization involving very different time scales. The Compton polarimeter has achieved the design goals of 1% statistical uncertainty per hour and we expect to achieve less than 1% systematic uncertainty.

A concept of high intensity femtosecond laser synchrotron source (LSS) is based on Compton backscattering of focused electron and laser beams. The short Rayleigh length of the focused laser beam limits the length of interaction to a few picoseconds. However, the technology of the high repetition rate high-average power picosecond lasers required for high put through LSS applications is not developed yet. Another problem associated with the picosecond laser pulses is undesirable nonlinear effects occurring when the laser photons are concentrated in a short time interval. To avoid the nonlinear Compton scattering, the laser beam has to be split, and the required hard radiation flux is accumulated over a number of consecutive interactions that complicates the LSS design. In order to relieve the technological constraints and achieve a practically feasible high-power laser synchrotron source, the authors propose to confine the laser-electron interaction region in the extended plasma channel. This approach permits to use nanosecond laser pulses instead of the picosecond pulses. That helps to avoid the nonlinear Compton scattering regime and allows to utilize already existing technology of the high-repetition rate TEA CO{sub 2} lasers operating at the atmospheric pressure. They demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider.

The information theoretic technique of entropy maximization is applied to Compton profile (CP) data, employing single and double distribution moments Compton profile J(q). The quality of resulting maximum entropy profiles is judged by how well they predict familiar CP quantities—moments, the profiles' magnitude at the origin J(0), and the width at half-maximum q0.5. Information theoretic quantities—Shannon entropies, information contents, and surprisals—are also presented. Based upon the ''sum'' constraint Compton profiles. The average momentum constraint contains the most information of all moment expectation values, as judged by its predictive capacity and by the information theory measures.

A feasibility study has been performed to determine the potential usefulness of Compton imaging as a tool for design information verification (DIV) of uranium enrichment plants. Compton imaging is a method of gamma-ray imaging capable of imaging with a 360-degree field of view over a broad range of energies. These systems can image a room (with a time span on the order of one hour) and return a picture of the distribution and composition of radioactive material in that room. The effectiveness of Compton imaging depends on the sensitivity and resolution of the instrument as well the strength and energy of the radioactive material to be imaged. This study combined measurements and simulations to examine the specific issue of UF{sub 6} gas flow in pipes, at various enrichment levels, as well as hold-up resulting from the accumulation of enriched material in those pipes. It was found that current generation imagers could image pipes carrying UF{sub 6} in less than one hour at moderate to high enrichment. Pipes with low enriched gas would require more time. It was also found that hold-up was more amenable to this technique and could be imaged in gram quantities in a fraction of an hour. another questions arises regarding the ability to separately image two pipes spaced closely together. This depends on the capabilities of the instrument in question. These results are described in detail. In addition, suggestions are given as to how to develop Compton imaging as a tool for DIV.

High-energy x-ray backlighters will be valuable for radiography experiments at the National Ignition Facility (NIF), and for radiography of imploded inertial confinement fusion cores using Compton scattering to observe cold, dense plasma. Key considerations are the available backlight brightness, and the backlight size. To quantify these parameters we have characterized the emission from low- and high-Z planar foils irradiated by intense picosecond and femtosecond laser pulses from the TITAN laser facility at Lawrence Livermore National Laboratory. Spectra generated by a sequence of elements from Mo to Pb, spanning the x-ray energy range from 17 keV to 75 keV, have been recorded using a Charged Coupled Device (CCD) in single hit regime and a Dual Crystal Spectrometer (DCS). High-resolution point-projection 2D radiographs have also been recorded on Fuji BaFBr:Eu2 image plates using calibrated resolution grids. We discuss the results in light of the requirements for applications at NIF.

We propose to build and test a hodoscopic CsI(Tl) scintillating-crystal calorimeter for a medium-energy γ-ray Compton and pair telescope. The design and technical approach for this calorimeter relies deeply on heritage from the Fermi LAT CsI Calorimeter, but it dramatically improves the low-energy performance of that design by reading out the scintillation light with silicon photomultipliers (SiPMs), making the technology developed for Fermi applicable in the Compton regime. While such a hodoscopic calorimeter is useful for an entire class of medium-energy γ-ray telescope designs, we propose to build it explicitly to support beam tests and balloon flight of the Proto-ComPair telescope, the development and construction of which was funded in a four-year APRA program beginning in 2015 ("ComPair: Steps to a Medium Energy γ-ray Mission" with PI J. McEnery of GSFC). That award did not include funding for its CsI calorimeter subsystem, and this proposal is intended to cover that gap. ComPair is a MIDEX-class instrument concept to perform a high-sensitivity survey of the γ-ray sky from 0.5 MeV to 500 MeV. ComPair is designed to provide a dramatic increase in sensitivity relative to previous instruments in this energy range (predominantly INTEGRAL/SPI and Compton COMPTEL), with the same transformative sensitivity increase – and corresponding scientific return– that the Fermi Large Area Telescope provided relative to Compton EGRET. To enable transformative science over a broad range of MeV energies and with a wide field of view, ComPair is a combined Compton telescope and pair telescope employing a silicon-strip tracker (for Compton scattering and pair conversion and tracking) and a solid-state CdZnTe calorimeter (for Compton absorption) and CsI calorimeter (for pair calorimetry), surrounded by a plastic scintillator anti-coincidence detector. Under the current proposal, we will complete the detailed design, assembly, and test of the CsI calorimeter for the risk

modeled using MCNPX Version 2.5.0. The Compton suppression mechanism is integrated into the phoswich design to effectively reduce the Compton continuum...background radiation was modeled using MCNPX Version 2.5.0. The Compton suppression mechanism is integrated into the phoswich design to effectively reduce...be calculated through regions of interest corresponding to the four xenon radioisotopes in the 2D spectrum. An alternative solution to measure

Computer simulations of cylindrical Compton Ar-Xe gamma camera are described in the current report. Detection efficiency of cylindrical Ar-Xe Compton camera with internal diameter of 40 cm is estimated as1-3%that is 10-100 times higher than collimated Anger’s camera. It is shown that cylindrical Compton camera can image Tc-99m radiotracer distribution with uniform spatial resolution of 20 mm through the whole field of view.

This study involved identifying, categorizing, and comparing critical incidents related to qualifying dual credit high school students' decisions to enroll or not to enroll in dual credit coursework in either a traditional or early college high school. The purpose of the study was (a) to identify the reasons qualifying students decide to enroll in…

Purpose Despite the practice of dual leadership in many organizations, there is relatively little research on the topic. Dual leadership means two leaders share the leadership task and are held jointly accountable for the results of the unit. To better understand how dual leadership works, this study aims to analyse three different dual leadership pairs at a Danish hospital. Furthermore, this study develops a tool to characterize dual leadership teams from each other. Design/methodology/approach This is a qualitative study using semi-structured interviews. Six leaders were interviewed to clarify how dual leadership works in a hospital context. All interviews were transcribed and coded. During coding, focus was on the nine principles found in the literature and another principle was found by looking at the themes that were generic for all six interviews. Findings Results indicate that power balance, personal relations and decision processes are important factors for creating efficient dual leaderships. The study develops a categorizing tool to use for further research or for organizations, to describe and analyse dual leaderships. Originality/value The study describes dual leadership in the hospital context and develops a categorizing tool for being able to distinguish dual leadership teams from each other. It is important to reveal if there are any indicators that can be used for optimising dual leadership teams in the health-care sector and in other organisations.

Measurement of combustion gas by high-energy X-ray Compton scattering is reported. The intensity of Compton-scattered X-rays has shown a position dependence across the flame of the combustion gas, allowing us to estimate the temperature distribution of the combustion flame. The energy spectra of Compton-scattered X-rays have revealed a significant difference across the combustion reaction zone, which enables us to detect the combustion reaction. These results demonstrate that high-energy X-ray Compton scattering can be employed as an in situ technique to probe inside a combustion reaction.

The recent discoveries of Sw J1644+57 and Sw J2058+05 show that tidal disruption events (TDEs) can launch relativistic jets. Super-Eddington accretion produces a strong radiation field of order Eddington luminosity. In a jetted TDE, electrons in the jet will inverse-Compton scatter the photons from the accretion disc and wind (external radiation field). Motivated by observations of thermal optical-UV spectra in Sw J2058+05 and several other TDEs, we assume the spectrum of the external radiation field intercepted by the relativistic jet to be blackbody. Hot electrons in the jet scatter this thermal radiation and produce luminosities 1045-1048 erg s- 1 in the X/γ-ray band. This model of thermal plus inverse-Compton radiation is applied to Sw J2058+05. First, we show that the blackbody component in the optical-UV spectrum most likely has its origin in the super-Eddington wind from the disc. Then, using the observed blackbody component as the external radiation field, we show that the X-ray luminosity and spectrum are consistent with the inverse-Compton emission, under the following conditions: (1) the jet Lorentz factor is Γ ≃ 5-10; (2) electrons in the jet have a power-law distribution dN_e/dγ _e ∝ γ _e^{-p} with γmin ˜ 1 and p = 2.4; (3) the wind is mildly relativistic (Lorentz factor ≳ 1.5) and has isotropic-equivalent mass-loss rate ˜ 5 M⊙ yr- 1. We describe the implications for jet composition and the radius where jet energy is converted to radiation.

Gammasphere, the national {gamma}-ray facility, when completed will consist of 110 Compton-suppressed Ge detectors. The bismuth germanate (BGO) Compton-suppression detector system for each Ge detector consists of one tapered hexagonal BGO side shield and one slotted BGO back plug. Due to the geometry of the array, three types of annular shields are required. These types are referred to as B, C and D, and the array consists of 60, 30 and 20 of these units, respectively. Shield types B, C and D have a hexagonal geometry. They are divided into six optically separate sections, each with its own pair of photomultiplier tubes. Argonne assumed responsibility for the procurement and testing of the BGO Compton-suppression units. We received all detectors from the two vendors. In the past year, twenty-four of the B-type detectors were delivered to Stony Brook for evaluation tests. Since the number of crystals to test is quite large (six per detector), we involved undergraduate students working at ANL under the Department of Educational Programs (DEP) in this effort. The quality of students was excellent, and they played a major role in the performance testing of these detectors. Ninety-nine of the hexagonal side shields and 112 backplug detectors were shipped to LBL for use in Gammasphere. The remaining detectors did not meet the performance criteria when they were first delivered and tested and are either at the vendor being repaired or were returned to us for retesting. We anticipate that the remaining detectors will be ready for use in Gammasphere within the next few months.

We present the spin momentum density of Ga doped CoFe{sub 2}O{sub 4} at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe{sub 2}O{sub 4}.

The paper describes a 50-cm-diam prototype of a novel Compton-scattering-type polarimeter for hard X-rays in the energy range 30-100 keV. The characteristics of the prototype polarimeter were investigated for various conditions. It was found that, with polarized X-rays from a simple polarizer, the detection efficiency and the modulation factor of the polarimeter with a 40-mm thick scatterer were 3.2 percent and 0.57 percent, respectively, at about 60 keV.

The Compton Spectrometer and Imager (COSI), which was formerly known as the Nuclear Compton Telescope (NCT), is a balloon-borne soft gamma-ray telescope (0.2-5 MeV) designed to probe the origins of Galactic positrons, uncover sites of nucleosynthesis in the Galaxy, and perform pioneering studies of gamma-ray polarization in a number of source classes. COSI uses a compact Compton telescope design, resulting from a decade of development under NASA's ROSES program - a modern take on techniques successfully pioneered by COMPTEL on CGRO. We have rebuilt the COSI instrument and flight systems, upgraded for balloon flights and improved polarization sensitivity. We will present the redesign of COSI and the overall goals of the 5-year science program. Three science flights are planned to fulfill the COSI science goals: an LDB in 2014 from Antarctica on a superpressure balloon (SuperCOSI), followed by two 100-day ULDB flights from New Zealand. COSI is a wide-field survey telescope designed to perform imaging, spectroscopy, and polarization measurements. It employs a novel Compton telescope design utilizing a compact array of cross-strip germanium detectors (GeDs) to resolve individual gamma-ray interactions with high spectral and spatial resolution. The COSI array is housed in a common vacuum cryostat cooled by a mechanical cryocooler. An active CsI shield encloses the cryostat on the sides and bottom. The FoV of the instrument covers 25% of the full sky at a given moment. The COSI instrument is mature, building upon considerable heritage from the previous NCT balloon instrument that underwent a successful technology demonstration flight in June 2005 from Fort Sumner, NM, a successful "first light" science flight from Fort Sumner in May 2009, and quickly turned around and delivered on time for a launch campaign from Alice Springs, Australia in June 2010, where it unfortunately suffered a launch mishap. The NCT instrument and Flight System are being rebuilt under the NASA

A method for the conversion of Compton camera data into a 2D image of the incident-radiation flux on the celestial sphere includes detecting coincident gamma radiation flux arriving from various directions of a 2-sphere. These events are mapped by back-projection onto the 2-sphere to produce a convolution integral that is subsequently stereographically projected onto a 2-plane to produce a second convolution integral which is deconvolved by the Fourier method to produce an image that is then projected onto the 2-sphere.

It was found that the traditional first-order Compton-Getting effect, which relates particle distributions as observed in two frames of reference moving with constant relative velocity, is inadequate for the description of low energy particles (less than a few hundred keV/nucleon) in the solar system. An exact procedure is given for recovering both isotropic and anisotropic distributions in the solar wind frame from observations made in a spacecraft frame. The method was illustrated by analyzing a particle event observed on IPM-7.

The Time Projection Compton Spectrometer (TPCS) is a radiation diagnostic designed to determine the time-integrated energy spectrum between 100 keV -- 2 MeV of flash x-ray sources. This guide is intended as a reference for the routine operator of the TPCS. Contents include a brief overview of the principle of operation, detailed component descriptions, detailed assembly and disassembly procedures, guide to routine operations, and troubleshooting flowcharts. Detailed principle of operation, signal analysis and spectrum unfold algorithms are beyond the scope of this guide; however, the guide makes reference to sources containing this information.

A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. Here we discuss two options for transverse magnetic bunch compression and final focus, each involving a 4-dipole chicane with M_{56} tunable over a range of 1.5-2.0m with independent tuning of final focus to interaction point $\\beta$*=5mm. One design has no net bending, while the other has net bending of 90 degrees and is suitable for compact corner placement.

The Compton Spectrometer and Image (COSI) is a ULDB-borne soft gamma-ray telescope (0.2-5 MeV) designed to probe the origins of Galactic positrons, uncover sites of nucleosynthesis in the Galaxy, and perform pioneering studies of gamma-ray polarization in a number of source classes. COSI uses a compact Compton telescope design, resulting from a decade of development under NASA’s ROSES program - a modern take on techniques successfully pioneered by COMPTEL on CGRO. COSI performs groundbreaking science by combining improvements in sensitivity, spectral resolution, and sky coverage. The COSI instrument and flight systems have been designed for flight on NASA’s 18 MCF superpressure balloon (SPB). We are now beginning a series science flights to fulfill the COSI science goals: a SPB in 2014 from Antarctica, followed by two 100-day ULDB flights from New Zealand.COSI is a wide-field survey telescope designed to perform imaging, spectroscopy, and polarization measurements. It employs a novel Compton telescope design utilizing a compact array of cross-strip germanium detectors (GeDs) to resolve individual gamma-ray interactions with high spectral and spatial resolution. The COSI array is housed in a common vacuum cryostat cooled by a mechanical cryocooler. An active CsI Shield encloses the cryostat on the sides and bottom. The FoV of the instrument covers 25% of the full sky at a given moment.The COSI instrument builds upon considerable heritage from the previous Nuclear Compton Telescope (NCT) balloon instrument that underwent a successful technology demonstration flight in June 2005 from Fort Sumner, NM, a successful “first light” science flight from Fort Sumner in May 2009, and a launch campaign from Alice Springs, Australia in June 2010, where it unfortunately suffered a launch mishap. COSI has been upgraded from the previous NCT instrument by conversion to a detector configuration optimized for polarization sensitivity and addition of a cryocooler to remove

The reduction of a particle s wave function in the process of radiation or light scattering is a longstanding problem. Its solution will give a clue on processes that form, for example, wave functions of electrons constantly emitting synchrotron radiation quanta in storage rings. On a more global scale, it may shed light on wave function collapse due to the process of measurement. In this paper we consider various experimental options using Fermilab electron beams and a possible electron beam from the SNS linac and lasers to detect electron wave function change due to Compton scattering.

Radiation reaction effects in the interaction of an electron and a strong laser field are investigated in the realm of quantum electrodynamics. We identify the quantum radiation reaction with the multiple photon recoils experienced by the laser-driven electron due to consecutive incoherent photon emissions. After determining a quantum radiation dominated regime, we demonstrate how in this regime quantum signatures of the radiation reaction strongly affect multiphoton Compton scattering spectra and that they could be measurable in principle with presently available laser technology.

Radiation reaction effects in the interaction of an electron and a strong laser field are investigated in the realm of quantum electrodynamics. We identify the quantum radiation reaction with the multiple photon recoils experienced by the laser-driven electron due to consecutive incoherent photon emissions. After determining a quantum radiation dominated regime, we demonstrate how in this regime quantum signatures of the radiation reaction strongly affect multiphoton Compton scattering spectra and that they could be measurable in principle with presently available laser technology.

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The cross sections for Compton scattering from positronium are calculated in the range from 1 to 100 keV incident photon energy. The calculations are based on the A{sup 2} term of the photon-electron or photon-positron interaction. Unlike in hydrogen, the scattering occurs from two centers and the interference effect plays an important role for energies below 8 keV. Because of the interference, the criterion for validity of the impulse approximation for positronium is more restrictive compared to that for hydrogen.

We study the performance of a large-scale Compton imaging detector placed in a low-flying aircraft, used to search wide areas for rad/nuc threat sources. In this paper we investigate the performance potential of equipping aerial platforms with gamma-ray detectors that have photon sensitivity up to a few MeV. We simulate the detector performance, and present receiver operating characteristics (ROC) curves for a benchmark scenario using a {sup 137}Cs source. The analysis uses a realistic environmental background energy spectrum and includes air attenuation.

Einstein and Ehrenfest's radiation theory is modified in order to take into account the effects of the random zero-point fields, characteristic of classical stochastic electrodynamics, in a system of classical molecules interacting with thermal radiation. This is done by replacing the Einstein concept of “random spontaneous emission” by the concept of stimulated emission by the random zero-point fields. As a result, Compton and Debye's kinematic relations are obtained within the realm of a completely classical theory, that is, without having to consider the wave-particle duality for the molecules or the radiation.

Compton scattering from the proton was investigated at s=6.9 GeV{sup 2} and t=-4.0 GeV{sup 2} via polarization transfer from circularly polarized incident photons. The longitudinal and transverse components of the recoil proton polarization were measured. The results are in disagreement with a prediction of perturbative QCD based on a two-gluon exchange mechanism, but agree well with a prediction based on a reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.

The Jefferson Lab Hall A experiment E99-114 comprised a series of measurements to explore proton Compton scattering at high momentum transfer. For the first time, the polarisation transfer observables in the p ($\\vec{γ}$, γ' \\vec{p}$) reaction were measured in the GeV energy range, where it is believed that quark-gluon degrees of freedom begin to dominate. The experiment utilised a circularly polarised photon beam incident on a liquid hydrogen target, with the scattered photon and recoil proton detected in a lead-glass calorimeter and a magnetic spectrometer, respectively.

... OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.2 Purpose. The purpose of this part is to specify one of the criteria in 49 U.S.C. chapter 329 “Automobile Fuel Economy” for identifying dual-fueled passenger automobiles that are manufactured in model years 1993 through 2019. The...

... OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.2 Purpose. The purpose of this part is to specify one of the criteria in 49 U.S.C. chapter 329 “Automobile Fuel Economy” for identifying dual-fueled passenger automobiles that are manufactured in model years 1993 through 2019. The...

... OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.2 Purpose. The purpose of this part is to specify one of the criteria in 49 U.S.C. chapter 329 “Automobile Fuel Economy” for identifying dual-fueled passenger automobiles that are manufactured in model years 1993 through 2019. The...

... OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.2 Purpose. The purpose of this part is to specify one of the criteria in 49 U.S.C. chapter 329 “Automobile Fuel Economy” for identifying dual-fueled passenger automobiles that are manufactured in model years 1993 through 2019. The...

... OF TRANSPORTATION MANUFACTURING INCENTIVES FOR ALTERNATIVE FUEL VEHICLES § 538.2 Purpose. The purpose of this part is to specify one of the criteria in 49 U.S.C. chapter 329 “Automobile Fuel Economy” for identifying dual-fueled passenger automobiles that are manufactured in model years 1993 through 2019. The...

... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Control purposes. 730.6 Section 730.6... Control purposes. The export control provisions of the EAR are intended to serve the national security... carry out its international obligations. Some controls are designed to restrict access to dual use...

We report here a simple Compton scattering experiment which may be carried out in graduate and undergraduate laboratories to determine the rest mass energy of the electron. In the present experiment, we have measured the energies of the Compton scattered gamma rays with a NaI(Tl) gamma ray spectrometer coupled to a 1 K multichannel analyzer at…

The Generalized Parton Distributions (GPDs) are a more general formalism englobing the concept of elastic form factor (FF) and parton distributions (PDFs) introducing a third independent variable called skewdness xi in addition to usual x_bj and t variables which are defined for the PDFs. Those distributions thus contain more information than the FF and PDFs allowing to give a more spatial and dynamical description of the nucleon. To measure GPDs one has to measure exclusive reaction. The simplest exclusive reaction is the exclusive production of photons or Deeply Virtual Compton Scattering. One drawback of this measurement is that the real photon constrains the measurement of the GPDs to the line xi =x. The Doubly Virtual Compton Scattering (DDVCS) is the similar process involving a virtual photon in the final state. This virtual photon decays into a dilepton pair allowing some values of xi different than x_bj. High luminosity is required since cross sections are smaller by a factor 100. I will present options to try to measure the DDVCS process particularly in the dimuon channel using the JLab 12 GeV beam.

The Compton Gamma Ray Observatory was the second of NASA's Great Observatories. At 17 1/2 tons. it was the heaviest astrophysical payload ever flown at the time of its launch on April 5, 1991 aboard the Space Shuttle. During initial, on-orbit priming of the spacecraft's monopropellant hydrazine propulsion system, a severe waterhammer transient was experienced. At that time, anomalous telemetry readings were received from on-board propulsion system instrumentation. This led to ground analyses and laboratory investigations as to the root cause of the waterhammer, potential damage to system integrity and functionality, and risks for switching from the primary (A-side) propulsion system to the redundant (B-side) system. The switchover to B-side was ultimately performed successfully and the spacecraft completed its basic and extended missions in this configuration. Nine years later, following a critical control gyroscope failure, Compton was safely deorbited and re-entered the Earth's atmosphere on June 4, 2000. Additional risk assessments concerning viability of A- and B-sides were necessary to provide confidence in attitude and delta-V authority and reliability to manage the precisely controlled reentry. This paper summarizes the design and operation of the propulsion system used on the spacecraft and provides "lessons learned" from the system engineering investigations into the propellant loading procedures, the initial priming anomaly, mission operations, and the commanded re-entry following the gyro failure.

Past research has shown that anti-coincidence shielded Ge(Li) spectrometers enhanced the signal-to-background ratios for gamma-photopeaks, which are situated on high Compton backgrounds. Ordinarily, an anti- or non-coincidence spectrum (A) and a coincidence spectrum (C) are collected simultaneously with these systems. To be useful in neutron activation analysis (NAA), the fractions of the photopeak counts routed to the two spectra must be constant from sample to sample to variations must be corrected quantitatively. Most Compton suppression counting has been done at low count rate, but in NAA applications, count rates may be much higher. To operate over the wider dynamic range, the effect of count rate on the ratio of the photopeak counts in the two spectra (A/C) was studied. It was found that as the count rate increases, A/C decreases for gammas not coincident with other gammas from the same decay. For gammas coincident with other gammas, A/C increases to a maximum and then decreases. These results suggest that calibration curves are required to correct photopeak areas so quantitative data can be obtained at higher count rates. ?? 1984.

The Compton scattering of the light on the accelerated electron beam is a valuable tool for generating tunable wide range X- and γ-radiation.However, the cross-section of the scattering is relatively low. That is, in order to obtain bright X-rays one naturally may consider increasing the intensity of the incident light. Passing to relativistic values of laser intensity significantly changes scattering mechanism. Precise QED analysis of the scattered spectra leads to the study of the corresponding elements of S-matrix. Evaluation is usually performed numerically (except cases of specific pulse shapes and scattering angles). We argue that the problem of extracting the scattered spectra in nonlinear Compton scattering of the pulse can be reformulated in terms of studying properties of projection map of specific surfaces associated to the pulse. They are stable with respect to initial conditions, and the brightest regions of the spectrum appear to be in correspondence with the singularities of the projection map, also known as caustics in pure mathematics, diffraction optics and cosmology. Work was supported by the Helmholtz Association (Helmholtz Young Investigators group VH-NG-1037).

A method has been proposed to utilize the well-known Compton scattering process as a tool to measure the centroid energy of a high energy electron beam at the 0.01% level. It is suggested to use the Compton scattering of an infrared laser off the electron beam, and then to measure the energy of the scattered gamma-rays very precisely using solid-state detectors. The technique proposed is applicable for electron beams with energies from 200 MeV to 16 GeV using presently available lasers. This technique was judged to be the most viable of all those proposed for beam energy measurements at the nearby Continuous Electron Beam Accelerator Facility (CEBAF). Plans for a prototype test of the technique are underway, where the main issues are the possible photon backgrounds associated with an electron accelerator and the electron and laser beam stabilities and diagnostics. The bulk of my ASEE summer research has been spent utilizing the expertise of the staff at the Aerospace Electronics Systems Division at LaRC to assist in the design of the test. Investigations were made regarding window and mirror transmission and radiation damage issues, remote movement of elements in ultra-high vacuum conditions, etc. The prototype test of the proposed laser backscattering method is planned for this December.

Bright AGN frequently show ultrafast outflows (UFOs) with outflow velocities vout ˜ 0.1c. These outflows may be the source of AGN feedback on their host galaxies sought by galaxy formation modellers. The exact effect of the outflows on the ambient galaxy gas strongly depends on whether the shocked UFOs cool rapidly or not. This in turn depends on whether the shocked electrons share the same temperature as ions (one-temperature regime, 1T) or decouple (2T), as has been recently suggested. Here we calculate the inverse Compton spectrum emitted by such shocks, finding a broad feature potentially detectable either in mid-to-high energy X-rays (1T case) or only in the soft X-rays (2T). We argue that current observations of AGN do not seem to show evidence for the 1T component. The limits on the 2T emission are far weaker, and in fact it is possible that the observed soft X-ray excess of AGN is partially or fully due to the 2T shock emission. This suggests that UFOs are in the energy-driven regime outside the central few pc, and must pump considerable amounts of not only momentum but also energy into the ambient gas. We encourage X-ray observers to look for the inverse Compton components calculated here in order to constrain AGN feedback models further.

AGN exhibit complex hard X-ray spectra. Our current understanding is that the emission is dominated by inverse Compton processes which take place in the corona above the accretion disk, and that absorption and reflection in a distant absorber play a major role. These processes can be directly observed through the shape of the continuum, the Compton reflection hump around 30 keV, and the iron fluorescence line at 6.4 keV. We demonstrate the capabilities of Simbol-X to constrain complex models for cases like MCG-05-23-016, NGC 4151, NGC 2110, and NGC 4051 in short (10 ksec) observations. We compare the simulations with recent observations on these sources by INTEGRAL, Swift and Suzaku. Constraining reflection models for AGN with Simbol-X will help us to get a clear view of the processes and geometry near to the central engine in AGN, and will give insight to which sources are responsible for the Cosmic X-ray background at energies >20 keV.

Using Monte Carlo simulation, the authors investigate algorithms to identify and correct for detector Compton scatter in hypothetical PET modules with 3 x 3 x 30 mm BGO crystals coupled to individual photosensors. Rather than assume a particular design, they study three classes of detectors: (1) with energy resolution limited by counting statistics, (2) with energy resolution limited by electronic noise, and (3) with depth of interaction (DOI) measurement capability. For the first two classes, selecting the channel with the highest signal as the crystal of interaction yields a 22--25% misidentification fraction (MIF) for all reasonable noise fwhm to signal (N/S) ratios (i.e. < 0.5 at 511 keV). Algorithms that attempt to correctly position events that undergo forward Compton scatter using only energy information can reduce the MIF to 12%, and can be easily realized with counting statistics limited detectors but can only be achieved with very low noise values for noise limited detectors. When using position of interaction to identify forward scatter, a MIF of 12% can be obtained if the detector has good energy and position resolution.

We review the current state of knowledge of the nucleon polarizabilities and of their role in nucleon Compton scattering and in hydrogen spectrum. We discuss the basic concepts, the recent lattice QCD calculations and advances in chiral effective-field theory. On the experimental side, we review the ongoing programs aimed to measure the nucleon (scalar and spin) polarizabilities via the Compton scattering processes, with real and virtual photons. A great part of the review is devoted to the general constraints based on unitarity, causality, discrete and continuous symmetries, which result in model-independent relations involving nucleon polarizabilities. We (re-)derive a variety of such relations and discuss their empirical value. The proton polarizability effects are presently the major sources of uncertainty in the assessment of the muonic hydrogen Lamb shift and hyperfine structure. Recent calculations of these effects are reviewed here in the context of the "proton-radius puzzle". We conclude with summary plots of the recent results and prospects for the near-future work.

The factorizable form of the relativistic impulse approximation (RIA) expression for Compton scattering doubly differential cross sections (DDCS) becomes progressively less accurate as the binding energy of the ejected electron increases. This expression, which we call the RKJ approximation, makes it possible to obtain the Compton profile (CP) from measured DDCS. We have derived three simple analytic expressions, each which can be used to correct the RKJ error for the atomic K-shell CP obtained from DDCS for any atomic number Z. The expression which is the most general is valid over a broad range of energy ω and scattering angle θ, a second expression which is somewhat simpler is valid at very high ω but over most θ, and the third which is the simplest is valid at small θ over a broad range of ω. We demonstrate that such expressions can yield a CP accurate to within a 1% error over 99% of the electron momentum distribution range of the Uranium K-shell CP. Since the K-shell contribution dominates the extremes of the whole atom CP (this is where the error of RKJ can exceed an order of magnitude), this region can be of concern in assessing the bonding properties of molecules as well as semiconducting materials.

The authors have performed neutron Compton scattering measurements on ammonium hexachloropalladate (NH4)2PdCl6 and ammonium hexachlorotellurate (NH4)2TeCl6. Both substances belong to the family of ammonium metallates. The aim of the experiment was to investigate the possible role of electronic environment of a proton on the anomaly of the neutron scattering intensity. The quantity of interest that was subject to experimental test was the reduction factor of the neutron scattering intensities. In both samples, the reduction factor was found to be smaller than unity, thus indicating the anomalous neutron Compton scattering from protons. Interestingly, the anomaly decreases with decreasing scattering angle and disappears at the lowest scattering angle (longest scattering time). The dependence of the amount of the anomaly on the scattering angle (scattering time) is the same in both substances (within experimental error). Also, the measured widths of proton momentum distributions are equal in both metallates. This is consistent with the fact that the attosecond proton dynamics of ammonium cations is fairly well decoupled from the dynamics of the sublattice of the octahedral anions PdCl62- and TeCl62-, respectively. The hypothesis is put forward that proton-electron decoherence processes are responsible for the considered effect. Decoherence processes may have to do rather with the direct electronic environment of ammonium protons and not with the electronic structure of the metal-chlorine bond.

This paper presents a feasibility study of a Compton scattering enhanced (CSE) multiple pinhole imaging system for gamma rays with energy of 140keV or higher. This system consists of a multiple-pinhole collimator, a position sensitive scintillation detector as used in standard Gamma camera, and a Silicon pad detector array, inserted between the collimator and the scintillation detector. The problem of multiplexing, normally associated with multiple pinhole system, is reduced by using the extra information from the detected Compton scattering events. In order to compensate for the sensitivity loss, due to the low probability of detecting Compton scattered events, the proposed detector is designed to collect both Compton scattering and Non-Compton events. It has been shown that with properly selected pinhole spacing, the proposed detector design leads to an improved image quality.

Calculations of X-Ray production rates, energy spread, and spectrum of Compton-backscattered photons from a Free Electron Laser on an electron beam in a low energy (136-MeV) compact (8.5-m circumference) storage ring indicate that an X-Ray intensity of 34.6 10{sup 7} X-Ray photons per 0.5-mm {times} 0.5-mm pixel for Coronary Angiography near the 33.169-keV iodine K-absorption edge can be achieved in a 4-msec pulse within a scattering cone of 1-mrad half angle. This intensity, at 10-m from the photon-electron interaction point to the patient is about a factor of 10 larger than presently achieved from a 4.5-T superconducting wiggler source in the NSLS 2.5-GeV storage ring and over an area about 5 times larger. The 2.2-keV energy spread of the Compton-backscattered beam is, however, much larger than the 70-eV spread presently attained form the wiggler source and use of a monochromator. The beam spot at the 10-m interaction point-to-patient distance is 20-mm diameter; larger spots are attainable at larger distances but with a corresponding reduction in X-Ray flux. Such a facility could be an inexpensive clinical alternative to present methods of non-invasive Digital Subtraction Angiography (DSA), small enough to be deployed in an urban medical center, and could have other medical, industrial and aerospace applications. Problems with the Compton backscattering source include laser beam heating of the mirror in the FEL oscillator optical cavity, achieving a large enough X-Ray beam spot at the patient, and obtaining radiation damping of the transverse oscillations and longitudinal emittance dilution of the storage ring electron beam resulting from photon-electron collisions without going to higher electron energy where the X-Ray energy spread becomes excessive for DSA. 38 refs.

We describe a project to develop new medium-energy gamma-ray instrumentation by constructing and flying a balloon-borne Compton telescope using advanced scintillator materials combined with silicon photomultiplier readouts. There is a need in high-energy astronomy for a medium-energy gamma-ray mission covering the energy range from approximately 0.4 - 20 MeV to follow the success of the COMPTEL instrument on CGRO. We believe that directly building on the legacy of COMPTEL, using relatively robust, low-cost, off-the-shelf technologies, is the most promising path for such a mission. Fortunately, high-performance scintillators, such as Lanthanum Bromide (LaBr3), Cerium Bromide (CeBr3), and p-terphenyl, and compact readout devices, such as silicon photomultipliers (SiPMs), are already commercially available and capable of meeting this need. We have conducted two balloon flights of prototype instruments to test these technologies. The first, in 2011, demonstrated that a Compton telescope consisting of an liquid organic scintillator scattering layer and a LaBr3 calorimeter effectively rejects background under balloon-flight conditions, using time-of-flight (ToF) discrimination. The second, in 2014, showed that a telescope using an organic stilbene crystal scattering element and a LaBr3 calorimeter with SiPM readouts can achieve similar ToF performance. We are now constructing a much larger balloon instrument, an Advanced Scintillator Compton Telescope (ASCOT) with SiPM readout, with the goal of imaging the Crab Nebula at MeV energies in a one-day flight. We expect a 4σ detection up to 1 MeV in a single transit. We present calibration results of the first detector modules, and updated simulations of the balloon instrument sensitivity. If successful, this project will demonstrate that the energy, timing, and position resolution of this technology are sufficient to achieve an order of magnitude improvement in sensitivity in the mediumenergy gamma-ray band, were it to be

The Q-weak experiment aims to measure the weak charge of proton with a precision of 4.2%. The proposed precision on weak charge required a 2.5% measurement of the parity violating asymmetry in elastic electron - proton scattering. Polarimetry was the largest experimental contribution to this uncertainty and a new Compton polarimeter was installed in Hall C at Jefferson Lab to make the goal achievable. In this polarimeter the electron beam collides with green laser light in a low gain Fabry-Perot Cavity; the scattered electrons are detected in 4 planes of a novel diamond micro strip detector while the back scattered photons are detected in lead tungstate crystals. This diamond micro-strip detector is the first such device to be used as a tracking detector in a nuclear and particle physics experiment. The diamond detectors are read out using custom built electronic modules that include a preamplifier, a pulse shaping amplifier and a discriminator for each detector micro-strip. We use field programmable gate array based general purpose logic modules for event selection and histogramming. Extensive Monte Carlo simulations and data acquisition simulations were performed to estimate the systematic uncertainties. Additionally, the Moller and Compton polarimeters were cross calibrated at low electron beam currents using a series of interleaved measurements. In this dissertation, we describe all the subsystems of the Compton polarimeter with emphasis on the electron detector. We focus on the FPGA based data acquisition system built by the author and the data analysis methods implemented by the author. The simulations of the data acquisition and the polarimeter that helped rigorously establish the systematic uncertainties of the polarimeter are also elaborated, resulting in the first sub 1% measurement of low energy (?1 GeV) electron beam polarization with a Compton electron detector. We have demonstrated that diamond based micro-strip detectors can be used for tracking in a

Purpose: Development of a photon detection system designed for online range verification of laser-accelerated proton beams via prompt-gamma imaging of nuclear reactions. Methods: We develop a Compton camera for the position-sensitive detection of prompt photons emitted from nuclear reactions between the proton beam and biological samples. The detector is designed to be capable to reconstruct the photon source origin not only from the Compton scattering kinematics of the primary photon, but also to allow for tracking of the Compton-scattered electrons. Results: Simulation studies resulted in the design of the Compton camera based on a LaBr{sub 3}(Ce) scintillation crystal acting as absorber, preceded by a stacked array of 6 double-sided silicon strip detectors as scatterers. From the design simulations, an angular resolution of ≤ 2° and an image reconstruction efficiency of 10{sup −3} −10{sup −5} (at 2–6 MeV) can be expected. The LaBr{sub 3} crystal has been characterized with calibration sources, resulting in a time resolution of 273 ps (FWHM) and an energy resolution of about 3.8% (FWHM). Using a collimated (1 mm diameter) {sup 137}Cs calibration source, the light distribution was measured for each of 64 pixels (6×6 mm{sup 2}). Data were also taken with 0.5 mm collimation and 0.5 mm step size to generate a reference library of light distributions that allows for reconstructing the interaction position of the initial photon using a k-nearest neighbor (k-NN) algorithm developed by the Delft group. Conclusion: The Compton-camera approach for prompt-gamma detection offers promising perspectives for ion beam range verification. A Compton camera prototype is presently being developed and characterized in Garching. Furthermore, an arrangement of, e.g., 4 camera modules could even be used in a ‘gamma-PET’ mode to detect delayed annihilation radiation from positron emitters in the irradiation interrupts (with improved performance in the presence of an

A new detector system, Polaris J from H3D, has been evaluated for its potential application as a Compton camera (CC) imaging device for prompt γ rays (PGs) emitted during proton radiation therapy (RT) for the purpose of dose range verification. This detector system consists of four independent CdZnTe detector stages and a coincidence module, allowing the user to construct a Compton camera in different geometrical configurations and to accept both double and triple scatter events. Energy resolution for the 662 keV line from 137Cs was found to be 9.7 keV FWHM. The raw absolute efficiencies for double and triple scatter events were 2.2 ×10-5 and 5.8 ×10-7, respectively, for γs from a 60Co source. The position resolution for the reconstruction of a point source from the measured CC data was about 2 mm. Overall, due to the low efficiency of the Polaris J CC, the current system was deemed not viable for imaging PGs emitted during proton RT treatment delivery. However, using a validated Monte Carlo model of the CC, we found that by increasing the size of the detectors and placing them in a two stage configuration, the efficiency could be increased to a level to make PG imaging possible during proton RT.

Compton camera prototype for a position-sensitive detection of prompt γ rays from proton-induced nuclear reactions is being developed in Garching. The detector system allows to track the Comptonscattered electrons. The camera consists of a monolithic LaBr3:Ce scintillation absorber crystal, read out by a multi-anode PMT, preceded by a stacked array of 6 double-sided silicon strip detectors acting as scatterers. The LaBr3:Ce crystal has been characterized with radioactive sources. Online commissioning measurements were performed with a pulsed deuteron beam at the Garching Tandem accelerator and with a clinical proton beam at the OncoRay facility in Dresden. The determination of the interaction point of the photons in the monolithic crystal was investigated.

Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this paper reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized at 5- and 15- pulses per train and compared to a single pulse operation under the same operating conditions. With the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.

This is the lead proposal for this program. We are proposing a 5-year program to perform the scientific flight program of the Nuclear Compton Telescope (NCT), consisting of a series of three (3) scientific balloon flights. NCT is a balloon-borne, wide-field telescope designed to survey the gamma-ray sky (0.2-5 MeV), performing high-resolution spectroscopy, wide-field imaging, and polarization measurements. NCT has been rebuilt as a ULDB payload under the current 2-year APRA grant. (In that proposal we stated our goal was to return at this point to propose the scientific flight program.) The NCT rebuild/upgrade is on budget and schedule to achieve flight-ready status in Fall 2013. Science: NCT will map the Galactic positron annihilation emission, shedding more light on the mysterious concentration of this emission uncovered by INTEGRAL. NCT will survey Galactic nucleosynthesis and the role of supernova and other stellar populations in the creation and evolution of the elements. NCT will map 26-Al and positron annihilation with unprecedented sensitivity and uniform exposure, perform the first mapping of 60-Fe, search for young, hidden supernova remnants through 44-Ti emission, and enable a host of other nuclear astrophysics studies. NCT will also study compact objects (in our Galaxy and AGN) and GRBs, providing novel measurements of polarization as well as detailed spectra and light curves. Design: NCT is an array of germanium gamma-ray detectors configured in a compact, wide-field Compton telescope configuration. The array is shielded on the sides and bottom by an active anticoincidence shield but is open to the 25% of the sky above for imaging, spectroscopy, and polarization measurements. The instrument is mounted on a zenith-pointed gondola, sweeping out ~50% of the sky each day. This instrument builds off the Compton telescope technique pioneered by COMPTEL on the Compton Gamma Ray Observatory. However, by utilizing modern germanium semiconductor strip detectors

We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new ``constituent quark model'' sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition we extract the J=0 pole contribution for both proton and nuclei. Using the modern high energy proton data we find that the J=0 pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman. We discuss phenomenological implications of this new result.

We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new “constituent quark model” sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition, we extract the α=0 pole contribution for both proton and nuclei. Using the modern high-energy proton data, we find that the α=0 pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman.

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and Φ, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and Φ, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axialmore » charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.« less

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep→e^{'}p^{'}γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ϕ, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for e p →e'p'γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2 , xB, t , and ϕ , for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

It is proposed that the gamma-ray photons that characterize the prompt emission of gamma-ray bursts are produced through the Compton-drag process, which is caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. This model accounts for the basic properties of gamma-ray bursts, i.e., the overall energetics, the peak frequency of the spectrum, and the fast variability, with an efficiency that can exceed 50%. In this scenario, there is no need for particle acceleration in relativistic collisionless shocks. Furthermore, although the Poynting flux may be important in accelerating the outflow, no magnetic field is required in the gamma-ray production. The drag also naturally limits the relativistic expansion of the fireball to Gamma less, similar104.

Image-guided surgery (IGS) is performed using a real-time surgery navigation system with three-dimensional (3D) position tracking of surgical tools. IGS is fast becoming an important technology for high-precision laparoscopic surgeries, in which the field of view is limited. In particular, recent developments in intraoperative imaging using radioactive biomarkers may enable advanced IGS for supporting malignant tumor removal surgery. In this light, we develop a novel intraoperative probe with a Compton camera and a position tracking system for performing real-time radiation-guided surgery. A prototype probe consisting of Ce :Gd3 Al2 Ga3 O12 (GAGG) crystals and silicon photomultipliers was fabricated, and its reconstruction algorithm was optimized to enable real-time position tracking. The results demonstrated the visualization capability of the radiation source with ARM = ∼ 22.1 ° and the effectiveness of the proposed system.

We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well.

The structure of Compton-heated coronae above accretion disks is studied here by using analytic and numerical approaches are used here to determine the direct and scattered radiation reaching the base of the corona for a range of central source luminosities. It is found that the outer region of the corona is unaffected by multiple scattering in the interior, provided that the luminosity of the central source is sufficient below the Eddington limit. How attenuation and scattering by the corona affects the strength of chromospheric emission lines is determined, as is the condition for which the irradiation due to the central source exceeds the locally generated flux from the disk. Finally, it is shown that the stability analysis for irradiated accretion disks of Tuchman et al. is not substantially altered by the corona.

The 30 keV peak in the X-ray background strongly suggests there should be a large number of highly obscured AGN in the local universe. However, the exact number of these objects remains unknown, even though they could nearly double the space density of supermassive black holes. These Compton-thick AGN can be detected in the hard X-rays with INTEGRAL. As part of the current observing cycle, we were awarded 2 Msec to perform INTEGRAL imaging of the XMM-LSS field in order to find highly obscured AGN in the local Universe. In this paper, we present preliminary results for the ˜1 Ms of IBIS data obtained so far, including new hard X-ray detections of AGN. We also present the 20---200 keV spectra of the brightest AGN including the z<0.1 Seyfert galaxies NGC 788, NGC 1068, and NGC 1142.

A data acquisition (DAQ) system with custom back-plane and custom readout boards has been developed for a Compton camera prototype. The DAQ system consists of two layers. The first layer has units for parallel high-speed analog-to-digital conversion and online data pre-processing. The second layer has a central board to form a general event trigger and to build the data structure for the event. This modularity and the use of field programmable gate arrays make the whole DAQ system highly flexible and adaptable to modified experimental setups. The design specifications, the general architecture of the Trigger and DAQ system and the implemented readout protocols are presented in this paper.

We study Compton scattering, {gamma}e {yields} {gamma}e, in the context of the recent proposal for Weak Scale Quantum Gravity (WSQG) with large extra dimensions. It is shown that, with an ultraviolet cutoff M{sub S} {approx} 1 TeV for the effective gravity theory, the cross section for this process at the Next Linear Collider (NLC) deviates from the prediction of the Standard Model significantly. Our results suggest that, for typical proposed NLC energies and luminosities, WSQG can be tested in the range 4 TeV {approx}< M{sub S} {approx}< 16 TeV, making {gamma}e {yields} {gamma}e an important test channel.

A Compton scatter camera based on position sensitive, planar Ge and Si(Li) detectors with segmented electrodes is being developed at LLNL. This paper presents various methods that were developed to increase the position resolution of the detectors, the granularity and capability to reconstruct the scattering sequence of the gamma-ray within the detectors. All these methods help to increase the efficiency of the imager, by accepting more photons in the final image. The initial extent and diffusion of charge-carrier clouds inside the semiconductor detectors are found to affect profoundly the fraction of interactions that deposit charge in multiple adjacent electrodes. An accurate identification of these charge-shared interactions is a key factor in correctly reconstructing the position of interactions in the detector.

The PorGamRays project aims to develop a portable gamma-ray detection system with both spectroscopic and imaging capabilities. The system is designed around a stack of thin Cadmium Zinc Telluride (CZT) detectors. The imaging capability utilises the Compton camera principle. Each detector is segmented into 100 pixels which are read out through custom designed Application Specific Integrated Circuits (ASICs). This device has potential applications in the security, decommissioning and medical fields. This work focuses on the near-field imaging performance of a lab-based demonstrator consisting of two pixelated CZT detectors, each of which is bonded to a NUCAM II ASIC. Measurements have been made with point 133Ba and 57Co sources located ˜35 mm from the surface of the scattering detector. Position resolution of ˜20 mm FWHM in the x and y planes is demonstrated.

The authors propose a measurement of the Deep Virtual Compton Scattering process (DVCS) ep {yields} ep{gamma} in Hall A at Jefferson Lab with a 6 GeV beam. The authors are able to explore the onset of Q{sup 2} scaling, by measuring a beam helicity asymmetry for Q{sup 2} ranging from 1.5 to 2.5 GeV{sup 2} at x{sub B} {approx} 0.35. At this kinematics, the asymmetry is dominated by the DVCS Bethe-Heitler (BH) interference, which is proportional to the imaginary part of the DVCS amplitude amplified by the full magnitude of the BH amplitude. The imaginary part of the DVCS amplitude is expected to scale early. Indeed, the imaginary part of the forward Compton amplitude measured in deep inelastic scattering (via the optical theorem) scales at Q{sup 2} as low as 1 GeV{sup 2}. If the scaling regime is reached, they make an 8% measurement of the skewed parton distributions (SPD) contributing to the DVCS amplitude. Also, this experiment allows them to separately estimate the size of the higher-twist effects, since they are only suppressed by an additional factor 1/Q compared to the leading-twist term, and have a different angular dependence. They use a polarized electron beam and detect the scattered electron in the HRSe, the real photon in an electromagnetic calorimeter (under construction) and the recoil proton in a shielded scintillator array (to be constructed). This allows them to determine the difference in cross-sections for electrons of opposite helicities. This observable is directly linked to the SPD's. The authors estimate that 25 days of beam (600 hours) are needed to achieve this goal.

Inverse Compton scattering of laser photons by ultrarelativistic electron beam provides polarized x- to γ -ray pulses due to the Doppler blueshifting. Nonlinear electrodynamics in the relativistically intense linearly polarized laser field changes the radiation kinetics established during the Compton interaction. These are due to the induced figure-8 motion, which introduces an overall redshift in the radiation spectrum, with the concomitant emission of higher order harmonics. To experimentally analyze the strong field physics associated with the nonlinear electron-laser interaction, clear modifications to the angular and wavelength distributions of x rays are observed. The relativistic photon wave field is provided by the ps CO2 laser of peak normalized vector potential of 0.5

Current methods for safeguarding and accounting for spent nuclear fuel in reprocessing facilities are extremely resource and time intensive. The incorporation of autonomous passive gamma-ray detectors into the procedure could make the process significantly less burdensome. In measured gamma-ray spectra from spent nuclear fuel, the Compton continuum from dominant fission product photopeaks obscure the lower energy lines from other isotopes. The application of Compton suppression to gamma-ray measurements of spent fuel may reduce this effect and allow other less intense, lower energy peaks to be detected, potentially improving the accuracy of multivariate analysis algorithms. Compton suppressed spectroscopic measurements of spent nuclear fuel using HPGe, LaBr3, and NaI(Tl) primary detectors were performed. Irradiated fuel was measured in two configurations: as intact fuel elements viewed through a collimator and as feed solutions in a laboratory to simulate the measurement of a dissolved process stream. These two configurations allowed the direct assessment and quantification of the differences in measured gamma-ray spectra from the application of Compton suppression. In the first configuration, several irradiated fuel elements of varying cooling times from the Penn State Breazeale Reactor spent fuel inventory were measured using the three collimated Compton suppression systems. In the second geometry, Compton suppressed measurements of two samples of Approved Test Material commercial fuel elements were recorded inside the guard detector annulus to simulate the siphoning of small quantities from the main process stream for long dwell measurement periods. Compton suppression was found to improve measured gamma-ray spectra of spent fuel for multivariate analysis by notably lowering the Compton continuum from dominant photopeaks such as 137Cs and 140La, due to scattered interactions in the detector, which allowed more spectral features to be resolved. There was a

Purpose: Computed Tomography (CT) is a method to produce slice image of specific volume from the scanned x-ray projection images. The contrast of CT image is correlated with the attenuation coefficients of the x-ray in the object. The attenuation coefficient is strongly dependent on the x-ray energy and the effective charge of the material. The purpose of this presentation is to show the effective charge distribution predicted by CT images reconstructed with kilovoltage(kV) and megavoltage(MV) x-ray energy. Methods: The attenuation coefficients of x-ray can be characterized by cross section of photoionization and Compton scattering for the specific xray energy. In particular, the photoionization cross section is strongly correlated with the effective charge of the object. Hence we can calculate effective charge by solving the coupled equation between the attenuation coefficient and the theoretical cross section. For this study, we use the megavoltage (MV) and kilovoltage (kV) x-rays of Elekta Synergy as the dual source x-ray, and CT image of the Phantom Laboratory CatPhan is reconstructed by the filtered back projection (FBP) and iterative algorithm for cone-beam CT (CBCT). Results: We report attenuation coefficients of each component of the CatPhan specified by each x-ray source. Also the effective charge distribution is evaluated by the MV and kV dual x-ray sources. The predicted effective charges are comparable with the nominal ones. Conclusion: We developed the MV and kV dual-source CBCT reconstruction to yield the effective charge distribution. For more accuracy, it is critical to remove an effect of the scattering photon in the CBCT reconstruction algorithm. The finding will be fine reference of the effective charge of tissue and lead to the more realistic absorbed-dose calculation. This work was partly supported by the JSPS Core-to-Core Program(No. 23003), and this work was partly supported by JSPS KAKENHI 24234567.

Stochastic image reconstruction has been applied to a dual-particle imaging system being designed for nuclear safeguards applications. The dual-particle imager (DPI) is a combined Compton-scatter and neutron-scatter camera capable of producing separate neutron and photon images. The stochastic origin ensembles (SOE) method was investigated as an imaging method for the DPI because only a minimal estimation of system response is required to produce images with quality that is comparable to common maximum-likelihood methods. This work contains neutron and photon SOE image reconstructions for a 252Cf point source, two mixed-oxide (MOX) fuel canisters representing point sources, and the MOX fuel canisters representing a distributed source. Simulation of the DPI using MCNPX-PoliMi is validated by comparison of simulated and measured results. Because image quality is dependent on the number of counts and iterations used, the relationship between these quantities is investigated.

New configurations of lasers and electron beams efficiently and robustly produce high flux beams of bright, tunable, polarized quasi-monoenergetic x-rays and gamma-rays via laser-Compton scattering. Specifically, the use of long-duration, pulsed lasers and closely-spaced, low-charge and low emittance bunches of electron beams increase the spectral flux of the Compton-scattered x-rays and gamma rays, increase efficiency of the laser-electron interaction and significantly reduce the overall complexity of Compton based light sources.

v2.2) Inverse- Compton emission from the lobes of 3C 353 J.L. Goodger,1⋆ M.J. Hardcastle,1 J.H. Croston,1 N.E. Kassim2 and R.A. Perley3 1University of...Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, USA ABSTRACT X-ray emission due to inverse- Compton scattering of microwave background photons...by electrons in the lobes of powerful radio galaxies has now been seen in a large number of objects. Combining an inverse- Compton model for the lobe

Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year.

Analytical properties of Compton profiles are used in order to simplify the analysis of neutron Compton scattering experiments. In particular, the possibility to fit the difference of Compton profiles is discussed as a way to greatly decrease the level of complexity of the data treatment, making the analysis easier, faster and more robust. In the context of the novel method proposed, two mathematical models describing the shapes of differenced Compton profiles are discussed: the simple Gaussian approximation for harmonic and isotropic local potential, and an analytical Gauss-Hermite expansion for an anharmonic or anisotropic potential. The method is applied to data collected by VESUVIO spectrometer at ISIS neutron and muon pulsed source (UK) on Copper and Aluminium samples at ambient and low temperatures.

The effect of Compton scattering on the ratio of double-to-single ionization from photon impact in helium has been measured for 2.1<=hν<=5.5 keV using a time-of-flight ion spectrometer with a high relative collection efficiency for Compton ions. Single ionization from Compton scattering is found to contribute measurably to a reduction in the ionization ratio for hν>~3.5 keV. Our measurements are compared with predictions based on recent calculations of the single and double ionization cross sections for photoabsorption and Compton scattering by Hino et al. [Phys. Rev. A 48, 1271 (1993), Phys. Rev. Lett. 72, 1620 (1994)], Andersson et al. [Phys. Rev. Lett. 71, 50 (1993)], and Surić et al. [Phys. Rev. Lett. 73, 790 (1994)].

Compton imaging is a useful method for localizing sub MeV to a few MeV gamma-rays and widely used for environmental and medical applications. The direction of recoiled electrons in Compton scattering process provides the additional information to limit the Compton cones and increases the sensitivity in the system. The capability of recoiled electron tracking using trigger-mode Silicon-On-Insulator (SOI) sensor is investigated with various radiation sources. The trigger-mode SOI sensor consists of 144 by 144 active pixels with 30 μm cells and the thickness of sensor is 500 μm. The sensor generates the digital output when it is hit by gamma-rays and 25 by 25 pixel pattern of surrounding the triggered pixel is readout to extract the recoiled electron track. The electron track is successfully observed for 60Co and 137Cs sources, which provides useful information for future electron tracking Compton camera.

We review theoretical progress and prospects to understand the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography.

We review theoretical progress and prospects for determining the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography.

We propose a time-of-flight (TOF) technique using plastic scintillators which have fast decay time of a few ns for positron emission tomography (PET). While the photoelectric absorption probability of the plastic for 511 keV gamma rays are extremely low due to its small density and effective atomic number, the cross section of Compton scattering is comparable to that of absorption by conventional inorganic scintillators. We thus propose TOF-PET using Compton scattering with plastic scintillators (Compton-PET), and performed fundamental experiments towards exploration of the Compton-PET capability. We demonstrated that the plastic scintillators achieved the better time resolution in comparison to LYSO(Ce) and GAGG(Ce) scintillators. In addition we evaluated the depth-of-interaction resolving capability with the plastic scintillators.

Gamma-ray imaging is useful for detecting, characterizing, and localizing sources in a variety of fields, including nuclear physics, security, nuclear accident response, nuclear medicine, and astronomy. Compton imaging in particular provides sensitivity to weak sources and good angular resolution in a large field of view. However, the photon origin in a single event sequence is normally only limited to the surface of a cone. If the initial direction of the Compton-scattered electron can be measured, the cone can be reduced to a cone segment with width depending on the uncertainty in the direction measurement, providing a corresponding increase in imaging sensitivity. Measurement of the electron's initial direction in an efficient detection material requires very fine position resolution due to the electron's short range and tortuous path. A thick (650 mum), fully-depleted charge-coupled device (CCD) developed for infrared astronomy has 10.5-mum position resolution in two dimensions, enabling the initial trajectory measurement of electrons of energy as low as 100 keV. This is the first time the initial trajectories of electrons of such low energies have been measured in a solid material. In this work, the CCD's efficacy as a gamma-ray detector is demonstrated experimentally, using a reconstruction algorithm to measure the initial electron direction from the CCD track image. In addition, models of fast electron interaction physics, charge transport and readout were used to generate modeled tracks with known initial direction. These modeled tracks allowed the development and refinement of the reconstruction algorithm. The angular sensitivity of the reconstruction algorithm is evaluated extensively with models for tracks below 480 keV, showing a FWHM as low as 20° in the pixel plane, and 30° RMS sensitivity to the magnitude of the out-of-plane angle. The measurement of the trajectories of electrons with energies as low as 100 keV have the potential to make electron

In outburst sources, quasi-periodic oscillation (QPO) frequency is known to evolve in a certain way: in the rising phase, it monotonically goes up until a soft intermediate state is achieved. In the propagating oscillatory shock model, oscillation of the Compton cloud is thought to cause QPOs. Thus, in order to increase QPO frequency, the Compton cloud must collapse steadily in the rising phase. In decline phases, the exact opposite should be true. We investigate cause of this evolution of the Compton cloud. The same viscosity parameter that increases the Keplerian disk rate also moves the inner edge of the Keplerian component, thereby reducing the size of the Compton cloud and reducing the cooling timescale. We show that cooling of the Compton cloud by inverse Comptonization is enough for it to collapse sufficiently so as to explain the QPO evolution. In the two-component advective flow configuration of Chakrabarti-Titarchuk, centrifugal force-induced shock represents the boundary of the Compton cloud. We take the rising phase of 2010 outburst of Galactic black hole candidate H 1743-322 and find an estimation of variation of the α parameter of the sub-Keplerian flow to be monotonically rising from 0.0001 to 0.02, well within the range suggested by magnetorotational instability. We also estimate the inward velocity of the Compton cloud to be a few meters per second, which is comparable to what is found in several earlier studies of our group by empirically fitting the shock locations with the time of observations.

A method for computing electron momentum densities and Compton profiles from ab initio calculations is presented. Reciprocal space is divided into optimally-shaped tetrahedra for interpolation, and the linear tetrahedron method is used to obtain the momentum density and its projections such as Compton profiles. Results are presented and evaluated against experimental data for Be, Cu, Ni, Fe3Pt, and YBa2Cu4O8, demonstrating the accuracy of our method in a wide variety of crystal structures.

The JLAB EIC (JLEIC) design includes a chicane after the interaction point to detect electron associated with production of quasi-real photon at the interaction. This chicane layout can also be used for Compton polarimetry to measure the electron beam polarization. This proceeding will present the layout of the low Q^2 chicane and the implementation and current R&D; of a Compton polarimeter which would be located in the middle of this chicane.

DESIGN OF A PARAXIAL INVERSE COMPTON SCATTERING DIAGNOSTIC FOR AN INTENSE RELATIVISTIC ELECTRON BEAM ∗ J.E. Colemanξ, J.A. Oertel, C.A. Ekdahl...supported by the National Nuclear Security Administration of the U.S. Department of Energy under ξ email: jecoleman@lanl.gov Abstract An inverse Compton ...ray range by the relativistic electrons. The diverging, scattered photons are diffracted onto an X-ray framing camera by an X-ray crystal

We describe a Direct Linear Algebraic Deconvolution (DLAD) approach to imaging of data from Compton gamma-ray telescopes. Imposition of the additional physical constraint, that all components of the model be non-negative, has been found to have a powerful effect in stabilizing the results, giving spatial resolution at or near the instrumental limit. A companion paper (Dixon et al. 1993) presents preliminary images of the Crab Nebula region using data from COMPTEL on the Compton Gamma-Ray Observatory.

Soft gamma repeaters and anomalous X-ray pulsars are subset of slow-rotating neutron stars, known as magnetars, that have extremely high inferred surface magnetic fields, of the order 100-1000 TeraGauss. Hard, non-thermal and pulsed persistent X-ray emission extending between 10 keV and 230 keV has been seen in a number of magnetars by RXTE, INTEGRAL, and Suzaku. In this thesis, the author considers inner magnetospheric models of such persistent hard X-ray emission where resonant Compton upscattering of soft thermal photons is anticipated to be the most efficient radiative process. This high efficiency is due to the relative proximity of the surface thermal photons, and also because the scattering becomes resonant at the cyclotron frequency. At the cyclotron resonance, the effective cross section exceeds the classical Thomson one by over two orders of magnitude, thereby enhancing the efficiency of continuum production and cooling of relativistic electrons. In this thesis, a new Sokolov and Ternov formulation of the QED Compton scattering cross section for strong magnetic fields is employed in electron cooling and emission spectra calculations. This formalism is formally correct for treating spin-dependent effects and decay rates that are important at the cyclotron resonance. The author presents electron cooling rates at arbitrary interaction points in a magnetosphere using the QED cross sections. The QED effects reduce the rates below high-field extrapolations of older magnetic Thomson results. The author also computes angle-dependent upscattering model spectra, formed using collisional integrals, for uncooled monoenergetic relativistic electrons injected in inner regions of pulsar magnetospheres. These spectra are integrated over closed field lines and obtained for different observing perspectives. The spectral cut-off energies are critically dependent on the observer viewing angles and electron Lorentz factor. It is found that electrons with energies less than

We present the first collective evidence that Fermi-detected jets of high kinetic power (L(sub kin)) are dominated by inverse Compton emission from upscattered external photons. Using a sample with a broad range in orientation angle, including radio galaxies and blazars, we find that very high power sources (L(sub kin) > 10(exp 45.5) erg/s) show a significant increase in the ratio of inverse Compton to synchrotron power (Compton dominance) with decreasing orientation angle, as measured by the radio core dominance and confirmed by the distribution of superluminal speeds. This increase is consistent with beaming expectations for external Compton (EC) emission, but not for synchrotron self Compton (SSC) emission. For the lowest power jets (L(sub kin) < 10(exp 43.5) erg /s), no trend between Compton and radio core dominance is found, consistent with SSC. Importantly, the EC trend is not seen for moderately high power flat spectrum radio quasars with strong external photon fields. Coupled with the evidence that jet power is linked to the jet speed, this finding suggests that external photon fields become the dominant source of seed photons in the jet comoving frame only for the faster and therefore more powerful jets.

The Nuclear Compton Telescope (NCT) is a balloon-borne Compton telescope designed for the study of astrophysical sources in the soft gamma-ray regime (200 keV-20 MeV). NCT's 10 high-purity germanium crossed-strip detectors measure the deposited energies and three-dimensional positions of gamma-ray interactions in the sensitive volume, and this information is used to restrict the initial photon to a circle on the sky using the Compton scatter technique. Thus NCT is able to perform spectroscopy, imaging, and polarization analysis on soft gamma-ray sources. NCT is one of the next generation of Compton telescopes—the so-called compact Compton telescopes (CCTs)—which can achieve effective areas comparable to the Imaging Compton Telescope's with an instrument that is a fraction of the size. The Crab Nebula was the primary target for the second flight of the NCT instrument, which occurred on 2009 May 17 and 18 in Fort Sumner, New Mexico. Analysis of 29.3 ks of data from the flight reveals an image of the Crab at a significance of 4σ. This is the first reported detection of an astrophysical source by a CCT.

We present the first collective evidence that Fermi-detected jets of high kinetic power (L kin) are dominated by inverse Compton emission from upscattered external photons. Using a sample with a broad range in orientation angle, including radio galaxies and blazars, we find that very high power sources (L kin > 1045.5 erg s-1) show a significant increase in the ratio of inverse Compton to synchrotron power (Compton dominance) with decreasing orientation angle, as measured by the radio core dominance and confirmed by the distribution of superluminal speeds. This increase is consistent with beaming expectations for external Compton (EC) emission, but not for synchrotron self-Compton (SSC) emission. For the lowest power jets (L kin < 1043.5 erg s-1), no trend between Compton and radio core dominance is found, consistent with SSC. Importantly, the EC trend is not seen for moderately high power flat spectrum radio quasars with strong external photon fields. Coupled with the evidence that jet power is linked to the jet speed, this finding suggests that external photon fields become the dominant source of seed photons in the jet comoving frame only for the faster and therefore more powerful jets.

In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing (22)Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3-5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy.

In order to exploit the advantages of ion-beam therapy in a clinical setting, delivery verification techniques are necessary to detect deviations from the planned treatment. Efforts are currently oriented towards the development of devices for real-time range monitoring. Among the different detector concepts proposed, Compton cameras are employed to detect prompt gammas and represent a valid candidate for real-time range verification. We present the first on-beam test of MACACO, a Compton telescope (multi-layer Compton camera) based on lanthanum bromide crystals and silicon photo-multipliers. The Compton telescope was first characterized through measurements and Monte Carlo simulations. The detector linearity was measured employing 22Na and Am-Be sources, obtaining about 10% deviation from linearity at 3.44 MeV. A spectral image reconstruction algorithm was tested on synthetic data. Point-like sources emitting gamma rays with energy between 2 and 7 MeV were reconstructed with 3-5 mm resolution. The two-layer Compton telescope was employed to measure radiation emitted from a beam of 150 MeV protons impinging on a cylindrical PMMA target. Bragg-peak shifts were achieved via adjustment of the PMMA target location and the resulting measurements used during image reconstruction. Reconstructed Bragg peak profiles proved sufficient to observe peak-location differences within 10 mm demonstrating the potential of the MACACO Compton Telescope as a monitoring device for ion-beam therapy.

Plutonium (Pu) contents in spent nuclear fuels, recovered uranium (U) or uranium/transuranium (U/TRU) products must be measured in order to secure the safeguardability of a pyroprocessing facility. Self-induced X-Ray fluorescence (XRF) and gamma-ray spectroscopy are useful techniques for determining Pu-to-U ratios and Pu isotope ratios of spent fuel. Photon measurements of spent nuclear fuel by using high-resolution spectrometers such as high-purity germanium (HPGe) detectors show a large continuum background in the low-energy region, which is due in large part to Compton scattering of energetic gamma rays. This paper proposes a Compton suppression system for reducing of the Compton continuum background. In the present study, the system was configured by using an HPGe main detector and a BGO (bismuth germanate: Bi4Ge3O12) guard detector. The system performances for gamma-ray measurement and XRF were evaluated by means of Monte Carlo simulations and measurements of the radiation source. The Monte Carlo N-Particle eXtended (MCNPX) simulations were performed using the same geometry as for the experiments, and considered, for exact results, the production of secondary electrons and photons. As a performance test of the Compton suppression system, the peak-to-Compton ratio, which is a figure of merit to evaluate the gamma-ray detection, was enhanced by a factor of three or more when the Compton suppression system was used.

The Nuclear Compton Telescope (NCT) is a balloon-borne Compton telescope designed for the study of astrophysical sources in the soft gamma-ray regime (200 keV-20 MeV). NCT's 10 high-purity germanium crossed-strip detectors measure the deposited energies and three-dimensional positions of gamma-ray interactions in the sensitive volume, and this information is used to restrict the initial photon to a circle on the sky using the Compton scatter technique. Thus NCT is able to perform spectroscopy, imaging, and polarization analysis on soft gamma-ray sources. NCT is one of the next generation of Compton telescopes-the so-called compact Compton telescopes (CCTs)-which can achieve effective areas comparable to the Imaging Compton Telescope's with an instrument that is a fraction of the size. The Crab Nebula was the primary target for the second flight of the NCT instrument, which occurred on 2009 May 17 and 18 in Fort Sumner, New Mexico. Analysis of 29.3 ks of data from the flight reveals an image of the Crab at a significance of 4{sigma}. This is the first reported detection of an astrophysical source by a CCT.

Compton imaging is a useful method to localize gamma sources without using mechanical collimators. In conventional Compton imaging, the incident directions of gamma rays are estimated in a cone for each event by analyzing the sequence of interactions of each gamma ray followed by Compton kinematics. Since the information of the ejection directions of the recoil electrons is lost, many artifacts in the shape of cone traces are generated, which reduces signal-to-noise ratio (SNR) and angular resolution. We have developed an advanced Compton imaging system with the capability of tracking recoil electrons by using a combination of a trigger-mode silicon-on-insulator (SOI) pixel detector and a GAGG detector. This system covers the 660-1330 keV energy range for localization of contamination nuclides such as 137Cs and 134Cs inside the Fukushima Daiichi Nuclear Power Plant in Japan. The ejection directions of recoil electrons caused by Compton scattering are detected on the micro-pixelated SOI detector, which can theoretically be used to determine the incident directions of the gamma rays in a line for each event and can reduce the appearance of artifacts. We obtained 2-D reconstructed images from the first iteration of the proposed system for 137Cs, and the SNR and angular resolution were enhanced compared with those of conventional Compton imaging systems.

Black hole accretion discs accreting near the Eddington rate are dominated by bremsstrahlung cooling, but above the Eddington rate the double Compton process can dominate in radiation-dominated regions while the cyclo-synchrotron can dominate in strongly-magnetized regions like in a corona or jet. We present an extension to the general relativistic radiation magnetohydrodynamic code HARMRAD to account for emission and absorption by thermal cyclo-synchrotron, double Compton, bremsstrahlung, low-temperature OPAL opacities as well as Thomson and Compton scattering. We approximate the radiation field as a Bose-Einstein distribution and evolve it using the radiation number-energy-momentum conservation equations in order to track photon hardening. We perform various simulations to study how these extensions affect the radiative properties of magnetically-arrested discs accreting at Eddington to super-Eddington rates. We find that double Compton dominates bremsstrahlung in the disc within a radius of r ˜ 15rg (gravitational radii) at a hundred times the Eddington accretion rate, and within smaller radii at lower accretion rates. Double Compton and cyclo-synchrotron regulate radiation and gas temperatures in the corona, while cyclo-synchrotron regulates temperatures in the jet. Interestingly, as the accretion rate drops to Eddington, an optically thin corona develops whose gas temperature of T ˜ 109K is ˜100 times higher than the disc's black body temperature. Our results show the importance of double Compton and synchrotron in super-Eddington discs, magnetized coronae, and jets.

We introduce a new method for treating Comptonization in computational fluid dynamics. By construction, this method conserves the number of photons. Whereas the traditional `blackbody Comptonization' approach assumes that the radiation is locally a perfect blackbody and therefore uses a single parameter, the radiation temperature, to describe the radiation, the new `photon-conserving Comptonization' approach treats the photon gas as a Bose-Einstein fluid and keeps track of both the radiation temperature and the photon number density. We have implemented photon-conserving Comptonization in the general relativistic radiation magnetohydrodynamical code KORAL and we describe its impact on simulations of mildly supercritical black hole accretion discs. We find that blackbody Comptonization underestimates the gas and radiation temperature by up to a factor of 2 compared to photon-conserving Comptonization. This discrepancy could be serious when computing spectra. The photon-conserving simulation indicates that the spectral colour correction factor of the escaping radiation in the funnel region of the disc could be as large as 5.

Bulk velocities exceed thermal velocities for sufficiently radiation pressure dominated accretion flows. We model the contribution of bulk Comptonization to the soft X-ray excess in AGN. Bulk Comptonization is due to both turbulence and the background shear. We calculate spectra both taking into account and not taking into account bulk velocities using scaled data from radiation magnetohydrodynamic (MHD) shearing box simulations. We characterize our results with temperatures and optical depths to make contact with other warm Comptonization models of the soft excess. We chose our fiducial mass, M = 2 × 106M⊙, and accretion rate, L/LEdd = 2.5, to correspond to those fit to the super-Eddington narrow line Seyfert 1 (NLS1) RE1034+396. The temperatures, optical depths, and Compton y parameters we find broadly agree with those fit to RE1034+396. The effect of bulk Comptonization is to shift the Wien tail to higher energy and lower the gas temperature, broadening the spectrum. Observations of the soft excess in NLS1s can constrain the properties of disc turbulence if the bulk Comptonization contribution can be separated out from contributions from other physical effects, such as reflection and absorption.

We are developing a Compton telescope based on high resolution Si and CdTe detectors for astrophysical observations in sub-MeV/MeV gamma-ray region. Recently, we constructed a prototype Compton telescope which consists of six layers of double-sided Si strip detectors and CdTe pixel detectors to demonstrate the basic performance of this new technology. By irradiating the detector with gamma-rays from radio isotope sources, we have succeeded in Compton reconstruction of images and spectra. The obtained angular resolution is 3.9{sup o} (FWHM) at 511 keV, and the energy resolution is 14 keV (FWHM) at the same energy. In addition to the conventional Compton reconstruction, i.e., drawing cones in the sky, we also demonstrated a full reconstruction by tracking Compton recoil electrons using the signals detected in successive Si layers. By irradiating {sup 137}Cs source, we successfully obtained an image and a spectrum of 662 keV line emission with this method. As a next step, development of larger double-sided Si strip detectors with a size of 4 cm x 4 cm is underway to improve the effective area of the Compton telescope. We are also developing a new low-noise analog ASIC to handle the increasing number of channels. Initial results from these two new technologies are presented in this paper as well.

Total Compton scattering cross sections and inelastic scattering factors for bound electron states of several elements have been evaluated in the framework of the relativistic impulse approximation (RIA). The accuracy of different approximate expressions for the singly differential cross section within the RIA is discussed. Accurate evaluations of bound state scattering factors require the use of the full RIA expression. Compton scattering from K-shell electrons dominates over the photoelectric absorption at higher energies. Energy values at which the Compton interaction become the main process of creation of K-shell vacancies are assessed. The role of binding effects in Compton processes at lower energies are clearly evidenced by the computed total cross sections. Calculated K-shell ionization total cross sections, defined as the sum of the photoelectric absorption and the Compton scattering cross sections, are in good agreement with available experimental data. The total Compton cross section for the 2s atomic orbital exhibits a shoulder-like structure, which can be traced back to the node structure of the 2s wave function.

The applicability of pQCD to exclusive reactions at medium energies is a subject of considerable interest. Real Compton scattering (RCS) has the potential to provide insight to this unsettled issue. In pQCD, three active quarks and two hard gluons are involved when describing RCS. But the cross sections do not agree with the pQCD predictions. In contrast, a handbag dominance model, involving only one single quark coupling to the spectator through generalized parton distributions (GPDs) does a good job of matching the cross section data. A measurement of the longitudinal polarization transfer parameter KLL was found inconsistent with predictions of pQCD yet consistent with calculations within the hand-bag mechanism. Further Miller's handbag approach, which including quark and hadron helicity flip, contradicts pQCD and others which demands that KLL =ALL , the initial state helicity correlation asymmetry, by finding that KLL ≠ALL . The first ever measurement of ALL has been proposed to run in Jefferson Lab's Hall C. This experiment will utilize an untagged bremsstrahlung photon beam and the longitudinally polarized UVA/JLAB proton target. After a brief introduction to the physics, the experiment will be described and the expected results presented.

POLAR is a compact wide field space-borne detector dedicated for precise measurements of the linear polarization of hard x-rays emitted by transient sources. Its energy range sensitivity is optimized for the detection of the prompt emission of Gamma-ray bursts (GRBs). POLAR is developed by an international collaboration of China, Switzerland and Poland. It is planned to be launched into space in 2016 onboard the Chinese space laboratory TG2. The energy range of POLAR spans between 50 keV and 500 keV. POLAR detects gamma rays with an array of 1600 plastic scintillator bars read out by 25 muti-anode PMTs (MAPMTs). Polarization measurements use Compton scattering process and are based on detection of energy depositions in the scintillator bars. Reconstruction of the polarization degree and polarization angle of GRBs requires comparison of experimental modulation curves with realistic simulations of the full instrument response. In this paper we present a method to model and parameterize the detector response including efficiency of the light collection, contributions from crosstalk and non-uniformity of MAPMTs as well as dependency on low energy detection thresholds and noise from readout electronics. The performance of POLAR for determination of polarization is predicted with such realistic simulations and carefully cross-checked with dedicated laboratory tests.

Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this article reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized at 5- and 15- pulses per train and compared to a single pulse operation under the same operating conditions. Lastly, with the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.

Wide-angle Compton scattering (WACS) belongs to the family of exclusive processes, with large values of s, - t , and - u , that can reveal nucleon structure. In the pQCD version of WACS, three active quarks and two hard gluons are required to share the momentum. pQCD predictions for the WACS disagree with the cross sections currently available. In contrast, handbag mechanism calculations involving a single quark coupled to the spectator through GPDs, are compatible with the cross sections. Measurements of the longitudinal polarization transfer parameter KLL have been found to be inconsistent with the predictions of pQCD yet consistent with calculations within the handbag mechanism, at least at very large angles. There are handbag calculations, including quark and hadron helicity flip, which contradicts pQCD by finding that KLL ≠ALL . A measurement of ALL has been approved to run at Jefferson Lab and which has the potential to clarify the nature of the reaction mechanism in WACS and illuminate the role of quark orbital angular momentum. It will utilize a pure untagged bremsstrahlung photon beam and a longitudinally polarized proton target. After an introduction, the experiment will be described and the expected results presented.

Whether pQCD can describe exclusive reactions at medium energies remains an area of active study. Real Compton scattering (RCS) has the potential to provide insight to this unsettled issue. A pQCD description of RCS requires the participation of three quarks and two hard gluons. However its predictions for the RCS cross sections disagree with data while calculations based on the handbag mechanism, involving a single quark coupled to the spectator through generalized parton distributions (GPDs), match the data well. The measured longitudinal polarization transfer parameter KLL is inconsistent with predictions of pQCD yet consistent with calculations of the handbag mechanism. Furthermore, Miller's approach, which includes quark and hadron helicity flip, contradicts pQCD where KLL =ALL , the initial state helicity correlation asymmetry, by finding that KLL ≠ALL . The first ever measurement of ALL (E12-14-006) has been approved to run in Jefferson Lab's Hall C and will be able to discriminate between the various models. E12-14-006 will utilize an untagged bremsstrahlung photon beam and the longitudinally polarized UVA/JLAB proton target. After a brief introduction to the physics, the experiment will be described and the expected results presented.

The Generalized Parton Distributions (GPDs) provide a new description of nucleon structure in terms of its elementary constituents, the quarks and the gluons. Including and extending the information provided by the form factors and the parton distribution functions, they describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark in the nucleon eN --> e'N'g, is the exclusive process most directly interpretable in terms of GPDs. A dedicated experiment to study DVCS with the CLAS detector at Jefferson Lab has been carried out using a 5.9-GeV polarized electron beam and an unpolarized hydrogen target, allowing us to collect DVCS events in the widest kinematic range ever explored in the valence region : 1.0 < Q2 < 4.6 GeV2, 0.1 < xB < 0.58 and 0.09 < -t < 2.0 GeV2. In this paper, we show preliminary results of unpolarized cross sections and of polarized cross section differences for the DVCS channel.

Theoretical isotropic (spherically symmetric) Compton profiles (ICP) have been calculated for many particle systems' He, Li, Be and B atoms in their ground states. Our calculations were performed using Roothan-Hartree-Fock (RHF) wave function, HF wave function of Thakkar and re-optimized HF wave function of Clementi-Roetti, taking into account the impulse approximation. The theoretical analysis included a decomposition of the various intra and inter shells and their contributions in the total ICP. A high momentum region of up to 4 a.u. was investigated and a non-negligible tail was observed in all ICP curves. The existence of a high momentum tail was mainly due to the electron-electron interaction. The ICP for the He atom has been compared with the available experimental data and it is found that the ICP values agree very well with them. A few low order radial momentum expectation values and the total energy for these atomic systems have also been calculated and compared with their counterparts' wave functions.

In a new experiment at the Final Focus Test Beam at SLAC a low- emittance 46.6 GeV electron beam is brought into collision with terawatt pulses from a 1.06 {mu} wavelength Nd:glass laser. Peak laser intensities of 10{sup 18} W/cm{sup 2} have been achieved corresponding to a value of 0.6 for the parameter {eta} = {ital eE/mw{sub 0}c}, and to a value of 0.3 for the parameter {Upsilon} = {ital E{sup *}/E{sub crit}} = 2{gamma}{ital ehE}/{ital m}{sup 2}{ital c}{sup 3} in the case of frequency doubled laser pulses. In these circumstances an electron that crosses the center of the laser pulse has near unit interaction probability. Signals are presented for multiphoton Compton scattering in which up to 4 laser photons interact with an electron. High energy backscattered photons of GeV energy can interact within the laser focus to create electron- positron pairs; an excess of 15 positrons above a background of 14 was observed in a run of 6,000 laser shots.

The enhanced Compton scattering in a supercavity has been observed experimentally. The supercavity with {approximately}99.99% reflectivity mirrors was used to confine the LD-pumped Nd:YAG laser light ({lambda} {approximately} 1.06 {mu} m, CW power {approximately} 500 mW, bandwidth <5kHz). The confined photons were scattered by 100kV electron beams generated from the laser-heated CW electrostatic accelerator. In this experiment, the scattered photon wavelength was in a visible range (<380nm). In order to increase the beam current and the system efficiency, the design of a beam recovery system is also in progress. As an alternative way to confine the laser power, a novel multi-pass optical resonator is being designed. 9MeV electron bunch from the rf linac with photoinjector will be used to interact with MW {approximately} TW high peak power laser pulse in the resonator. In this experiment, the scattered photon energy is in a x-ray regime. These experimental data is used to design the monochromatic {gamma}-ray sources for annihilation of the radioactive nuclear waste.

We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6d electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized then if the electron phase space is transformed in a way so that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6d photon phase space distribution) and derive it for the ICS source when the electron and laser rms matrices are arbitrary.

In the next generation of linear colliders, inverse Compton scattering (ICS) of intense laser pulses on relativistic electron bunches will enable a mode of operation based on energetic γe and γγ collisions, with a significant complementary scientific potential. The efficiency of γ-ray generation via ICS is constrained by the Thomson scattering cross section, resulting in typical laser photon-to- γ efficiencies of <10 -9. Furthermore, repetition rates of the state-of-art high-energy short-pulse lasers are poorly matched with those available from electron accelerators. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. We propose and experimentally demonstrate an alternative, non-interferometric method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J [ I. Jovanovic, M. Shverdin, D. Gibson, and C. Brown, Nucl. Instrum. Methods A 578 160 (2007)]. ICS of recirculated Joule-level laser pulses is compatible with the proposed pulse structure for ILC and has a potential to produce unprecedented peak and average γ-ray brightness in the next generation of sources.

An X-ray source utilizing Compton-backscattered (CB) photons in a 75-MeV electron storage ring containing an infrared FEL is proposed for producing 33.17-keV X-rays (Iodine K-edge) for coronary angiography. The X-ray intensity into a 4-mrad cone is computed as 7.21 {times} 10{sup 14}/sec for a 500-mA electron beam colliding with 0.2-J/bunch, 3.22-{mu}m photons from an in-ring IR-FEL at the 353.21-MHz rate of a SLAC-PEP 500-kW RF system. The resultant average flux at the patient is 6.4 {times} 10{sup 7} photons/pixel/4-msec aver a 12-cm diameter circle at 3-m from the interaction point for the 0.5 {times}0.5-mm{sup 2} pixel size of the present Si(Li) array of the BNL-SMERF Angiography Facility. This flux is 2.1 times larger than obtains at SMERF at a comparable source-to-patient distance and over an area sufficient to encompass the entire coronary region. However, the X-Ray energy spread due to kinematics alone is 2.63-keV, a factor of 35 larger then SMERF, and presents the major difficulty for the digital subtraction angiography method (DSA) envisioned.

Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this article reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized at 5-more » and 15- pulses per train and compared to a single pulse operation under the same operating conditions. Lastly, with the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.« less

Interactions between an electromagnetic wave and a proton are described at the basic level by the mass, charge, and anomalous magnetic moment of the proton. Such a description, however, assumes a point-like particle, something the proton is certainly not. The internal structure of the proton leads to higher order terms, such as the scalar and vector polarizabilities, in the interaction. To study these polarizabilities, a multi-experiment program has been undertaken at the Mainz Microtron to measure observables in Compton scattering that exhibit dependence on these parameters. This program has made use of the A2 tagged photon beam, with either a linear or circular polarization, proton targets of either unpolarized LH2 or frozen-spin butanol with transverse or longitudinal polarization, as well as the nearly 4 π detection capability of the Crystal Ball and TAPS detectors. The first of these measurements, the double-polarization asymmetry Σ2 x, also the first of its kind, has already been published. Measurements of the beam asymmetry Σ3 and another double-polarization asymmetry Σ2 z have also been performed and are in various stages of analysis and publication. This talk will discuss the status of these measurements, as well as various fitting studies that are being performed with the data in hand, and plans for future measurements. on behalf of the A2 collaboration at MAMI.

We analyze the characteristics of the γ radiation produced by Compton back-scattering of a high brightness electron beam produced by a photoinjector and accelerated in a linac up to energies of 360-720 MeV and a laser operated at about 500 nm, by comparing classical and quantum models and codes. The interaction produces γ rays in the range 4.9-18.8 MeV. In view of the application to nuclear resonance fluorescence a relative bandwidth of few 10-3 is needed. The bandwidth is reduced by taking advantage of the frequency-angular correlation typical of the phenomenon and selecting the radiation in an angle of tens of μrads. The foreseen spectral density is 20-6 photons per eV in a single shot, a number that can be increased by developing multi-bunch techniques and laser recirculation. In this way a final value of 104 photon per eV per second can be achieved.

The nucleon polarizabilities are fundamental structure observables, which describe its response to an applied electric or magnetic field. While the electric and magnetic scalar polarizabilities of the nucleon have been measured, little effort has been made to extract the spin dependent polarizabilities. These leading order spin dependent terms of the nucleon polarizabilities, γE1E1 ,γM1M1 ,γM1E2 and γE1M2 describe the spin response of a proton to electric and magnetic dipole and quadrupole interactions. We plan to extract these spin polarizabilities of the proton using real polarised Compton scattering off the proton at the MAMI tagged photon facility in Mainz, Germany. This requires precise measurement of the single and double polarization observables which are sensitive to these polarizabilities. The double polarization observables ∑2 x, ∑2 z are measured via a circulary polarized photon beam and a transversely and a linearly polarized butanol target in the resonance region (E = 250 - 310 MeV). This presentation will be focused on the status and analyis of an experiment completed at MAMI in 2014 and 2015 for the measurement of ∑2 z at different energies and angles. Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).

An X-ray source utilizing Compton-backscattered (CB) photons in a 75-MeV electron storage ring containing an infrared FEL is proposed for producing 33.17-keV X-rays (Iodine K-edge) for coronary angiography. The X-ray intensity into a 4-mrad cone is computed as 7.21 [times] 10[sup 14]/sec for a 500-mA electron beam colliding with 0.2-J/bunch, 3.22-[mu]m photons from an in-ring IR-FEL at the 353.21-MHz rate of a SLAC-PEP 500-kW RF system. The resultant average flux at the patient is 6.4 [times] 10[sup 7] photons/pixel/4-msec aver a 12-cm diameter circle at 3-m from the interaction point for the 0.5 [times]0.5-mm[sup 2] pixel size of the present Si(Li) array of the BNL-SMERF Angiography Facility. This flux is 2.1 times larger than obtains at SMERF at a comparable source-to-patient distance and over an area sufficient to encompass the entire coronary region. However, the X-Ray energy spread due to kinematics alone is 2.63-keV, a factor of 35 larger then SMERF, and presents the major difficulty for the digital subtraction angiography method (DSA) envisioned.

The medical isotope Molybdenum-99 is presently used for 80-85% of all nuclear medicine procedures and is produced by irradiating highly enriched uranium U-235 targets in NRU reactors. It was recently proposed that an electron linac be used for the production of 99Mo via photo-fission of a natural uranium target coming from the excitation of the giant dipole resonance around 15 MeV. The photons can be produced using the braking radiation (“bremsstrahlung”) spectrum of an electron beam impinged on a high Z material. In this paper we present an alternate concept for the production of 99Mo which is also based on photo-fission of U-238, but where the ~15 MeV gamma-rays are produced by Compton backscattering of laser photons from relativistic electrons. We assume a laser wavelength of 330 nm, resulting in 485 MeV electron beam energy, and 10 mA of average current. Because the induced energy spread on the electron beam is a few percent, one may recover most of the electron beam energy, which substantially increases the efficiency of the system. The accelerator concept, based on a three-pass recirculation system with energy recovery, is described and efficiency estimates are presented.

The proton spin-polarizabilities (SPs) are properties that quantify the response of the proton spin to electromagnetic waves. The SPs can be expressed in a linear combination called the backward spin polarizability (γπ) which arises in the cross-section of a Compton scattering event in which the incident photon is scattered at 180 degrees. As the cross-section at this angle cannot be experimentally determined, measurements of γπ are fitted using data with scattering angles close to 180 degrees. However, as the scattering angle is reduced the cross-section rapidly becomes determined by the values of the individual SPs, not γπ . This project investigated the viability of using cross-section data from different energy and angle bins to extract the γπ in order to optimize future experiments for γπ extraction. A Dispersion Relation was used to generate theory points based on randomly specified values of γπ and SPs for data sets of different energy and scattering angle. This was repeated 2000 times and the χ2 of each iteration was measured to determine if fits to a data set were dependent on the individual SPs values or γπ . This material is based upon work supported by the National Science Foundation under Grant No. IIA-1358175.

We investigate a novel scheme for significantly increasing the brightness of x-ray light sources based on inverse Compton scattering (ICS) - scattering laser pulses off relativistic electron beams. The brightness of ICS sources is limited by the electron beam quality, since electrons traveling at different angles, and/or having different energies, produce photons with different energies. Therefore, the spectral brightness of the source is defined by the 6D electron phase space shape and size, as well as laser beam parameters. The peak brightness of the ICS source can be maximized, then, if the electron phase space is transformed in a way such that all electrons scatter off the x-ray photons of same frequency in the same direction, arriving to the observer at the same time. We describe the x-ray photon beam quality through the Wigner function (6D photon phase space distribution), and derive it for the ICS source when the electron and laser rms matrices are arbitrary.

The Compton effect is a potential ionization mechanism of atoms. It produces vacancies in inner shells that are filled with the same mechanism of atomic relaxation as the one following photo-absorption. This contribution to X-ray fluorescence emission is frequently neglected because the total Compton cross-section is apparently much lower than the photoelectric one at useful X-ray energies. However, a more careful analysis suggests that is necessary to consider single shell cross sections (instead of total cross sections) as a function of energy. In this article these Compton cross sections are computed for the shells K, L1-L3 and M1-M5 in the framework of the impulse approximation. By comparing the Compton and the photoelectric cross-section for each shell it is then possible to determine the extent of the Compton correction to the intensity of the corresponding characteristic lines. It is shown that for the K shell the correction becomes relevant for excitation energies which are too high to be influent in X-ray spectrometry. In contrast, for L and M shells the Compton contribution is relevant for medium-Z elements and medium energies. To illustrate the different grades of relevance of the correction, for each ionized shell, the energies for which the Compton contribution reaches the extent levels of 1, 5, 10, 20, 50 and 100% of the photoelectric one are determined for all the elements with Z = 11-92. For practical applications it is provided a simple formula and fitting coefficients to compute average correction levels for the shells considered.

Dual wavelength lasers are discussed, covering fundamental aspects on the spectroscopy and laser dynamics of these systems. Results on Tm:Ho:Er:YAG dual wavelength laser action (Ho at 2.1 m and Er at 2.9 m) as well as Nd:YAG (1.06 and 1.3 m) are presented as examples of such dual wavelength systems. Dual wavelength lasers are not common, but there are criteria that govern their behavior. Based on experimental studies demonstrating simultaneous dual wavelength lasing, some general conclusions regarding the successful operation of multi-wavelength lasers can be made.

al. Enhancement of ectopic bone formation by bone morphogenetic protein-2 released from a heparin-conjugated poly(- L- lactic -co-glycolic acid ...release of antibiotic at an effective dose from the scaffolds for at least 6 weeks to ensure protection of the graft from colonization by bacteria . The...irrigated with 60 mL of saline.13 This period was chosen because it is clinically relevant14 and allows the bacteria enough time to attach to the

This procedure, using polystyrene spheres of specified diameter, renders the Millikan oil drop experiment more accurate than the conventional procedure of the polystyrene spheres, eliminates size estimation error, and removes the guesswork involved in assigning proper index integers to the observed charges. (MLH)

GRB 990123 was the first burst from which simultaneous optical, X-ray, and gamma-ray emission was detected; its afterglow has been followed by an extensive set of radio, optical, and X-ray observations. We have studied the gamma-ray burst itself as observed by the Compton Gamma Ray Observatory detectors. We find that gamma-ray fluxes are not correlated with the simultaneous optical observations and that the gamma-ray spectra cannot be extrapolated simply to the optical fluxes. The burst is well fitted by the standard four-parameter GRB function, with the exception that excess emission compared with this function is observed below approx. 15 keV during some time intervals. The burst is characterized by the typical hard-to-soft and hardness-intensity correlation spectral evolution patterns. The energy of the peak of the vf (sub v), spectrum, E (sub p), reaches an unusually high value during the first intensity spike, 1470 plus or minus 110 keV, and then falls to approx. 300 keV during the tail of the burst. The high-energy spectrum above approx. 1 MeV is consistent with a power law with a photon index of about -3. By fluence, GRB 990123 is brighter than all but 0.4% of the GRBs observed with BATSE (Burst and Transient Source Experiment), clearly placing it on the -3/2 power-law portion of the intensity distribution. However, the redshift measured for the afterglow is inconsistent with the Euclidean interpretation of the -3/2 power law. Using the redshift value of greater than or equal to 1.61 and assuming isotropic emission, the gamma-ray energy exceeds 10 (exp 54) ergs.

A new class of tunable, monochromatic {gamma}-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photoscience and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. A prototype, capable of producing > 10{sup 8} 0.7 MeV photons in a single shot, with a fractional bandwidth of 1%, and a repetition rate of 10 Hz, is currently under construction at LLNL; this system will be used to perform nuclear resonance fluorescence experiments. A new symmetrized S-band rf gun, using a Mg photocathode, will produce up to 1 nC of charge in an 8 ps bunch, with a normalized emittance modeled at 0.8 mm.mrad; electrons are subsequently accelerated up to 120 MeV to interact with a 500 mJ, 10 ps, 355 nm laser pulse and generate {gamma}-rays. The laser front end is a fiber-based system, using corrugated-fiber Bragg gratings for stretching, and drives both the frequency-quadrupled photocathode illumination laser and the Nd:YAG interaction laser. Two new technologies are used in the laser: a hyper-Michelson temporal pulse stacker capable of producing 8 ps square UV pulses, and a hyper-dispersion compressor for the interaction laser. Other key technologies, basic scaling laws, and recent experimental results will also be presented, along with an overview of future research and development directions.

The focus of this study has been to assess Compton suppressed gamma-ray detection systems for the multivariate analysis of spent nuclear fuel. This objective has been achieved using direct measurement of samples of irradiated fuel elements in two geometrical configurations with Compton suppression systems. In order to address the objective to quantify the number of additionally resolvable photopeaks, direct Compton suppressed spectroscopic measurements of spent nuclear fuel in two configurations were performed: as intact fuel elements and as dissolved feed solutions. These measurements directly assessed and quantified the differences in measured gamma-ray spectrum from the application of Compton suppression. Several irradiated fuel elements of varying cooling time from the Penn State Breazeale Reactor spent fuel inventory were measured using three Compton suppression systems that utilized different primary detectors: HPGe, LaBr3, and NaI(Tl). The application of Compton suppression using a LaBr3 primary detector to the measurement of the current core fuel element, which presented the highest count rate, allowed four additional spectral features to be resolved. In comparison, the HPGe-CSS was able to resolve eight additional photopeaks as compared to the standalone HPGe measurement. Measurements with the NaI(Tl) primary detector were unable to resolve any additional peaks, due to its relatively low resolution. Samples of Approved Test Material (ATM) commercial fuel elements were obtained from Pacific Northwest National Laboratory. The samples had been processed using the beginning stages of the PUREX method and represented the unseparated feed solution from a reprocessing facility. Compton suppressed measurements of the ATM fuel samples were recorded inside the guard detector annulus, to simulate the siphoning of small quantities from the main process stream for long dwell measurement periods. Photopeak losses were observed in the measurements of the dissolved ATM

At O (ω3) four new structure constants are present in the nucleon Compton scattering amplitude; these are the spin-polarizabilities γE 1 E 1, γM 1 M 1, γE 1 M 2, and γM 1 E 2. The most model independent way to determine the spin-polarizabilities is by measuring a double-polarized Compton scattering asymmetry with polarized target and circularly polarized photons, and by measuring an in-plane/transverse-plane Compton scattering asymmetry with linearly polarized photons (Σ3) . This talk will present new Compton scattering asymmetry data taken in the Δ region by the A2 Collaboration using the Crystal Ball at Mainz, with transverse polarized proton target and circularly polarized photons, the Σ2 x asymmetry (1). A dispersion model and an EFT calculation of Compton scattering are used to fit the four spin-polarizabilities to the new experimental data on Σ2 x, earlier results (2) on Σ3, and previous determinations of γ0 and γπ. The results of the fits are compared with theoretical calculations.

Knowledge of the electron beam polarization is one of the most important systematic uncertainties in precision, parity-violating electron scattering experiments with next generation experiments aiming to measure the electron beam polarization to better than 0.5%. At high energies, the most typical polarimetry techniques are Møller (polarized electron-electron) and Compton (polarized electron-photon) scattering. The use of two techniques with different systematic uncertainties provides confidence in the extracted beam polarization. Direct comparisons of the two polarimetry techniques are challenging in that Compton polarimeters typically desire maximum beam flux (high beam currents) while Møller polarimeters need to limit the beam current to avoid depolarization effects in the target. We have performed a direct comparison of the Møller and Compton polarimeters in experimental Hall C at Jefferson Lab. This test is unique in that the data were taken sequentially under identical beam conditions at 4.5 μA. We found excellent agreement between the Hall C Møller and Compton polarimeters. Combined with high-current Compton data, we were also able to limit the beam current dependence of the beam polarization to 1% or less up to a beam current of 180 μA. Supported in part by the U.S. Deparment of Energy, contract number AC05-06OR23177, under which Jefferson Science Associates, LLC operates Thomas Jefferson National Accelerator Facility.

The Compton camera, which shows gamma-ray distribution utilizing the kinematics of Compton scattering, is a promising detector capable of imaging across a wide range of energy. In this study, we aim to construct a small-animal molecular imaging system in a wide energy range by using the Compton camera. We developed a compact medical Compton camera based on a Ce-doped Gd3Al2Ga3O12 (Ce:GAGG) scintillator and multi-pixel photon counter (MPPC). A basic performance confirmed that for 662 keV, the typical energy resolution was 7.4 % (FWHM) and the angular resolution was 4.5° (FWHM). We then used the medical Compton camera to conduct imaging experiments based on a 3-D imaging reconstruction algorithm using the multi-angle data acquisition method. The result confirmed that for a 137Cs point source at a distance of 4 cm, the image had a spatial resolution of 3.1 mm (FWHM). Furthermore, we succeeded in producing 3-D multi-color image of different simultaneous energy sources (22Na [511 keV], 137Cs [662 keV], and 54Mn [834 keV]).

The possibility of using X-ray Compton scattering to reveal antisymmetric components of the electron momentum density, as a fingerprint of magnetoelectric sample properties, is investigated experimentally and theoretically by studying the polar ferromagnet GaFeO{sub 3}. This paper discusses the possibility of using Compton scattering – an inelastic X-ray scattering process that yields a projection of the electron momentum density – to probe magnetoelectrical properties. It is shown that an antisymmetric component of the momentum density is a unique fingerprint of such time- and parity-odd physics. It is argued that polar ferromagnets are ideal candidates to demonstrate this phenomenon and the first experimental results are shown, on a single-domain crystal of GaFeO{sub 3}. The measured antisymmetric Compton profile is very small (≃ 10{sup −5} of the symmetric part) and of the same order of magnitude as the statistical errors. Relativistic first-principles simulations of the antisymmetric Compton profile are presented and it is shown that, while the effect is indeed predicted by theory, and scales with the size of the valence spin–orbit interaction, its magnitude is significantly overestimated. The paper outlines some important constraints on the properties of the antisymmetric Compton profile arising from the underlying crystallographic symmetry of the sample.

Consideration is given to recent models for the cosmic X-ray background that assume that it originates from unresolved AGN emitting spectra due to enhanced Compton reflection of a power-law photon spectrum incident on cold matter. The parameter space of the Compton reflection model is studied, and the allowed parameter space is found to be severely constrained by physical and cosmological effects. For an incident power-law energy index alpha is greater than about 1, the X-ray peak in the observed spectrum from a population of AGN is necessarily at an energy less than that of the observed peak. Two examples of improved fits to the X-ray background are shown. It is concluded that the Compton reflection models proposed to date do not provide a straightforward explanation of the X-ray background spectrum.

The manganese sulfate bath technique is a standard tool for neutron source strength measurement (Park et al., 2005). However, the dominate Compton continuum of most sodium iodide scintillators used in manganese bath systems (MBSs) does not allow the precise identification of induced gamma rays required for such measurements. In this research, to resolve this problem, a Compton-suppression system has been proposed which consists of a 2 in. by 2 in. NaI(Tl) right cylindrical scintillator as the main and a set of eight rectangular NE102 plastic scintillators of 12×12×15 cm3 dimensions as suppression detectors. Both detectors operate in anti-coincidence circuit to suppress the Compton continuum. The proposed system has been simulated with the MCNPX code with two different approaches and the corresponding measurements with 137Cs gamma-ray source and neutron-activated MnSO4 solution have been undertaken that give rise to a promising agreement.

Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

X-ray sources based on the inverse Compton scattering process are attracting a growing interest among scientists, due to their extremely fast pulse, quasi-monochromatic spectrum, and relatively high intensity. The energy spectrum of the x-ray beam produced by inverse Compton scattering sources in a fixed observation direction is a quasi-monochromatic approximately Gaussian distribution. The mean value of this distribution varies with the scattering polar angle between the electron beam direction and the x-ray beam observation direction. Previous works reported experimental measurements of the mean energy as a function of the polar angle. This work introduces a method for the measurement of the whole local energy spectrum (i.e., the spectrum in a fixed observation direction) of the x-ray beam yielded by inverse Compton scattering sources, based on a k-edge filtering technique.

The generation of an isolated attosecond gamma-ray pulse utilizing Compton backscattering of a relativistic electron bunch has been investigated. The energy of the electron bunch is modulated while the electron bunch interacts with a co-propagating few-cycle CEP (carrier envelope phase)-locked laser in a single-period wiggler. The energy-modulated electron bunch interacts with a counter-propagating driver laser, producing Compton back-scattered radiation. The energy modulation of the electron bunch is duplicated to the temporal modulation of the photon energy of Compton back-scattered radiation. The spectral filtering using a crystal spectrometer allows one to obtain an isolated attosecond gamma-ray.

For Compton imaging it is necessary to determine the sequence of gamma-ray interactions in a single detector or array of detectors. This can be done by time-of-flight measurements if the interactions are sufficiently far apart. However, in small detectors the time between interactions can be too small to measure, and other means of gamma-ray sequencing must be used. In this work, several popular sequencing algorithms are reviewed for sequences with two observed events and three or more observed events in the detector. These algorithms can result in poor imaging resolution and introduce artifacts in the backprojection images. The effects of gamma-ray tracking algorithms on Compton imaging are explored in the context of the 4π Compton imager built by the University of Michigan.

A Compton scattering technique is presented to determine density and void location in the given wooden samples. The technique uses a well collimated gamma ray beam from {sup 137}Cs along with the NaI(Tl) scintillation detector. First, a linear relationship is established between Compton scattered intensity and known density of chemical compounds, and then density of the wood is determined from this linear relation. In another experiment, the ability of penetration of gamma rays is explored to detect voids in wooden (low Z) sample. The sudden reduction in the Compton scattered intensities agrees well with the position and size of voids in the wooden sample. It is concluded that wood density and the voids of size ∼ 4 mm and more can be detected easily by this method.

We investigate the effects of Lorentzian astrophysical plasmas on resonant Compton scattering of photons by the helium ground and excited states. The bound-excited states energies in the plasma environments are obtained by using highly correlated exponential wave functions in the framework of Ritz variational method. The resonance Compton scattering cross sections in Lorentzian plasmas between the 1s2{ }1S and 1s2p 1P, 1s2s 1S and 1s3p 1P, 1s3s 1S and 1s3d 1D states are reported as a function of the spectral index and plasma parameter. The nonthermal character of the Lorentzian plasmas shows interesting features on the resonant Compton scattering cross sections.

In this paper, we present the first-ever experimental Compton line shapes of HgBr(2) and HgI(2) using (137)Cs Compton spectrometer. To compare our experimental momentum densities, we have computed the Compton profiles using Hartree-Fock and density functional theory within linear combination of atomic orbitals. We have also computed the energy bands and density of states using the linear combination of atomic orbitals and full potential linearized augmented plane wave method. On the basis of equal-valence-electron-density profiles, it is seen that HgI(2) is more covalent than HgBr(2) which is in agreement with the valence charge densities. The experimental isotropic profiles are found to be relatively in better agreement with the Hartree-Fock data. We have also discussed the photoluminescence and detection properties of both the halides.

We present the first-ever experimental Compton profile of Laves phase ZrFe2 using indigenous 20 Ci 137Cs Compton spectrometer. To annotate the experimental electron momentum density, we have calculated the theoretical Compton profiles using density functional theory (DFT) and hybridization of Hartree-Fock and DFT within linear combination of atomic orbitals (LCAO) method. The spin-polarized energy bands and density of states are computed using LCAO and full potential-linearized augmented plane wave methods. The revised Perdew-Burke-Ernzerhof functional (for solids) based theoretical profile gives a marginally better agreement with the experimental profile as compared to other approximations considered in the present work. The Fermi surface topology of ZrFe2 is explained in terms of majority- and minority-spin energy bands.

In November 1941, the third of three reports on atomic fission commissioned by Vannevar Bush through the National Academy of Sciences examined the prospects for explosive fission in U-235. This report, prepared by Arthur Compton, developed a model for estimating the critical mass and efficiency of an atomic bomb. I examine Compton's physics, attempt to discern the provenance of the numbers he adopted for various parameters, and compare his results with those yielded by a full diffusion-theory approach with contemporary values for the fission parameters. I conclude that Compton's physics is sound. A combination of somewhat optimistic parameter values and a conservative model for critical mass lead him to a numerical value for the bare critical radius of U-235 that is in fairly good accord with that yielded by diffusion theory. His estimated efficiency proved to be quite accurate for the Little Boy bomb.

We present the design of a photon-photon collider based on conventional Compton gamma sources for the observation of elastic γ γ scattering. Two symmetric electron beams, generated by photocathodes and accelerated in linacs, produce two primary gamma rays through Compton backscattering with two high energy lasers. The elastic photon-photon scattering is analyzed by start-to-end simulations from the photocathodes to the detector. A new Monte Carlo code has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary gamma yield, obtained by using the parameters of existing or approved Compton devices, a discussion of the feasibility of the experiment and of the nature of the background are presented.

Compton imaging offers the possibility to improve significantly prostate imaging. Current radiotracer techniques, such as PET, SPECT or planar scintigraphy, suffer from photon attenuation in the tissue, poor resolution or low efficiency. The development of a Compton probe employing silicon as scatter detector makes possible to obtain a considerable benefit over present instrumentation. Electronic collimation overcomes the resolution-efficiency tradeoff imposed by mechanical collimators, and due to its near field operation, both high resolution and high counting efficiency can be achieved. Silicon pad sensors and low noise electronics are being optimized for this application. A Compton probe prototype has been developed, proving its viability and enabling further steps towards the construction of a clinical prototype.

Attention is given to a synchrotron self-Compton emission model for gamma-ray bursts which produces narrow annihilation features for a variety of field strengths, primary electron injection energies, and injection rates. In this model, primary electrons are injected and cooled by synchrotron emission in a strong, homogeneous magnetic field, resulting in a pair cascade. Multiple resonant scattering with cyclotron photons efficiently traps and cools pairs in the ground state to an average energy where the Compton energy loss rate is zero, which is in agreement with previous estimates of a Compton temperature. The particle distributions in the ground state are determined by numerically solving the Fokker-Planck equation in the steady state. In the case of isotropic injection of primary electrons, a significant narrow-line feature appears in the overall emission. In the case of beamed injection, the annihilation line is broadened to the extent that it would not be observable.

A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed.

Here we present new results of in situ nondestructive evaluation (NDE) of spacecraft thermal protection system materials obtained with POC-developed NDE tool based on a novel Compton Imaging Tomography (CIT) technique recently pioneered and patented by Physical Optics Corporation (POC). In general, CIT provides high-resolution three-dimensional Compton scattered X-ray imaging of the internal structure of evaluated objects, using a set of acquired two-dimensional Compton scattered X-ray images of consecutive cross sections of these objects. Unlike conventional computed tomography, CIT requires only one-sided access to objects, has no limitation on the dimensions and geometry of the objects, and can be applied to large multilayer non-uniform objects with complicated geometries. Also, CIT does not require any contact with the objects being imaged during its application.

Polarized gamma-rays were generated through laser-Compton backscattering (LCS) of a conventional Nd:YAG laser with electrons circulating in the electron storage ring TERAS at Electrotechnical Laboratory. We measured the energy, the energy spread, and the yield of the gamma-rays to characterize our gamma-ray source. The gamma-ray energy can be varied by changing the energy of the electrons circulating the storage ring. In our case, the energy of electrons in the storage ring were varied its energy from 200 to 750 MeV. Consequently, we observed gamma-ray energies of 1 to 10 MeV with 1064 run laser photons. Furthermore, the gamma-ray energy was extended to 20 MeV by using the 2nd harmonic of the Nd:YAG laser. This shows a good agreement with theoretical calculation. The gamma-ray energy spread was also measured to be 1% FWHM for -1 MeV gamma-rays and to be 4% FWHM for 10 MeV gamma-rays with a narrow collimator that defined the scattering cone. The gamma-ray yield was 47.2 photons/mA/W/s. This value is consistent with a rough estimation of 59.5 photons/mA/W/s derived from theory. Furthermore, we tried to use these gamma-rays for a nuclear fluorescence experiment. If we use a polarized laser beam, we can easily obtain polarized gamma-rays. Elastically scattered photons from {sup 208} Pb were clearly measured with the linearly polarized gamma-rays, and we could assign the parity of J=1 states in the nucleus. We should emphasize that the polarized gamma-ray from LCS is quit useful in this field, because we can use highly, almost completely, polarized gamma-rays. We also use the LCS gamma-rays to measure the photon absorption coefficients. In near future, we will try to generate a circular polarized gamma-ray. We also have a plan to use an FEL, because it can produce intense laser photons in the same geometric configuration as the LCS facility.

The purpose of this study was to compare the diagnostic accuracy of fluorine-18 fluorodeoxyglucose (FDG) images obtained with (a) a dual-head coincidence gamma camera (DHC) equipped with 5/8-inch-thick NaI(Tl) crystals and parallel slit collimators and (b) a dedicated positron emission tomograph (PET) in a series of 28 patients with known or suspected malignancies. Twenty-eight patients with known or suspected malignancies underwent whole-body FDG PET imaging (Siemens, ECAT 933) after injection of approximately 10 mCi of 18F-FDG. FDG DHC images were then acquired for 30 min over the regions of interest using a dual-head gamma camera (VariCam, Elscint). The images were reconstructed in the normal mode, using photopeak/photopeak, photopeak/Compton, and Compton/photopeak coincidence events. FDG PET imaging found 45 lesions ranging in size from 1 cm to 7 cm in 28 patients. FDG DHC imaging detected 35/45 (78%) of these lesions. Among the ten lesions not seen with FDG DHC imaging, eight were less than 1.5 cm in size, and two were located centrally within the abdomen suffering from marked attenuation effects. The lesions were classified into three categories: thorax (n=24), liver (n=12), and extrahepatic abdominal (n=9). FDG DHC imaging identified 100% of lesions above 1.5 cm in the thorax group and 78% of those below 1.5 cm, for an overall total of 83%. FDG DHC imaging identified 100% of lesions above 1.5 cm, in the liver and 43% of lesions below 1.5 cm, for an overall total of 67%. FDG DHC imaging identified 78% of lesions above 1.5 cm in the extrahepatic abdominal group. There were no lesions below 1.5 cm in this group. FDG coincidence imaging using a dual-head gamma camera detected 90% of lesions greater than 1.5 cm. These data suggest that DHC imaging can be used clinically in well-defined diagnostic situations to differentiate benign from malignant lesions.

A Compton polarimeter has been installed in Hall A at Jefferson Laboratory. This letter reports on the first electron beam polarization measurements performed during the HAPPEX experiment at an electron energy of 3.3 GeV and an average current of 40 muA. The heart of this device is a Fabry-Perot cavity which increased the luminosity for Compton scattering in the interaction region so much that a 1.4% statistical accuracy could be obtained within one hour, with a 3.3% total error.

The spin density of Heusler alloy Co 2FeGa, has been studied using the Compton scattering technique with 274 keV circularly polarized synchrotron radiation in the high energy inelastic scattering beamline (BL08W), at SPring-8, Japan. The magnetic Compton profiles along the two principal directions [1 1 0] and [1 1 1] were measured. The spin profiles shows a good agreement with our FLAPW-GGA results, where the theoretical results were based on the ferromagnetic ground state. The 3d spin moment at the Co and the Fe site was found to be in excellent agreement with the earlier reported neutron diffraction measurements.

In this paper space is modeled as a lattice of Compton wave oscillators (CWOs) of near- Planck size. It is shown that gravitation and special relativity emerge from the interaction between particles Compton waves. To develop this CWO model an algorithmic approach was taken, incorporating simple rules of interaction at the Planck-scale developed using well known physical laws. This technique naturally leads to Newton s law of gravitation and a new form of doubly special relativity. The model is in apparent agreement with the holographic principle, and it predicts a cutoff energy for ultrahigh-energy cosmic rays that is consistent with observational data.

Applications in nuclear medicine and bio-medical engineering may profit using a Compton camera for imaging distributions of radio-isotope labelled tracers in organs and tissues. These applications require detection of photons using thick position-sensitive silicon sensors with the highest possible energy and good spatial resolution. In this paper, research and development on silicon pad sensors and associated readout electronics for a Compton camera are presented. First results with low-noise, self-triggering VATAGP ASIC's are reported. The measured energy resolution was 1.1 keV FWHM at room temperature for the 241Am photo-peak at 59.5 keV.

In November 1941 Arthur Compton prepared a report for Vannevar Bush regarding the possibility of explosive fission of U-235. This remarkable report, arguably the parent document of the Los Alamos Primer, presented detailed estimates for the critical mass, expected energy release, efficiency, destructive effects and probable cost of such a weapon. This paper will examine the physics behind Compton's estimates for the critical mass and efficiency of a fission weapon and compare his results to those derived from present-day cross-sections and secondary-neutron numbers. His approach to the efficiency calculation is found to be particularly interesting in that it utilizes some very basic undergraduate physics.

A Monte Carlo simulation study has been conducted of 60Co photons Compton scattered in concrete, illustrating the degraded energy spectra of gamma-ray radiation. Results are produced representing a NaI(Tl) detector model. We were able to analyse energy distributions of photons that reach the detector system after suffering several successive Compton scatterings in the target. The predicted decrease in intensity of single- and multiple-scattering peaks with increase in thickness of the target medium are in good agreement with experimental observations and findings reported by others.

The {gamma} Compton scattering over a volume of concrete has been studied in order to design an instrument for density measurements. It will be used for the quality control in road construction, where large surfaces must be monitored. The experimental results and Monte Carlo simulations of the {gamma} Compton scattering over homogeneous and inhomogeneous volumes of concrete are shown. MC simulations have been useful to optimize the values of several parameters to improve the experimental set up and to estimate the extension of the explored volume.

Based on the high sensitivity of Compton scattering off ultra relativistic electrons, the possibility of anisotropies in the speed of light is investigated. The result discussed in this contribution is based on the γ-ray beam of the ESRF's GRAAL facility (Grenoble, France) and the search for sidereal variations in the energy of the Compton-edge photons. The absence of oscillations yields the two-sided limit of 1.6 × 10-14 at 95% confidence level on a combination of photon and electron coefficients of the minimal Standard-Model Extension (mSME). This new constraint provides an improvement over previous bounds by one order of magnitude.

Abstract Scenarios where the results of well-intentioned scientific research can be used for both good and harmful purposes give rise to what is now widely known as the “dual-use dilemma”. There has been growing debate about the dual-use nature of life science research with implications for making biological weapons. This paper reviews several controversial publications that have been the focus of debates about dual-use life science research and critically examines relevant policy developments, particularly in the United States of America. Though the dual-use dilemma is inherently ethical in nature, the majority of debates about dual-use research have primarily involved science and security experts rather than ethicists. It is important that there is more ethical input into debates about the governance of dual-use research. PMID:19784453

To address biosecurity issues, government agencies, academic institutions, and professional societies have developed policies concerning the publication of “dual-use” biomedical research—that is, research that could be readily applied to cause significant harm to the public, the environment, or national security. We conducted an e-mail survey of life science journals to determine the percentage that have a dual-use policy. Of the 155 journals that responded to our survey (response rate 39%), only 7.7% stated that they had a written dual-use policy and only 5.8% said they had experience reviewing dual-use research in the past 5 years. Among the potential predictors we investigated, the one most highly associated with a journal having a written dual-use policy was membership in the Nature Publishing Group (positive association). When considered individually, both previous experience with reviewing dual-use research and the journal's impact factor appeared to be positively associated with having a written dual-use policy, but only the former remained significant after adjusting for publishing group. Although preventing the misuse of scientific research for terrorist or criminal purposes is an important concern, few biomedical journals have dual-use review policies. Journals that are likely to review research that raises potential dual-use concerns should consider developing dual-use policies. PMID:21395429

To address biosecurity issues, government agencies, academic institutions, and professional societies have developed policies concerning the publication of "dual-use" biomedical research-that is, research that could be readily applied to cause significant harm to the public, the environment, or national security. We conducted an e-mail survey of life science journals to determine the percentage that have a dual-use policy. Of the 155 journals that responded to our survey (response rate 39%), only 7.7% stated that they had a written dual-use policy and only 5.8% said they had experience reviewing dual-use research in the past 5 years. Among the potential predictors we investigated, the one most highly associated with a journal having a written dual-use policy was membership in the Nature Publishing Group (positive association). When considered individually, both previous experience with reviewing dual-use research and the journal's impact factor appeared to be positively associated with having a written dual-use policy, but only the former remained significant after adjusting for publishing group. Although preventing the misuse of scientific research for terrorist or criminal purposes is an important concern, few biomedical journals have dual-use review policies. Journals that are likely to review research that raises potential dual-use concerns should consider developing dual-use policies.

We have recently shown that a 'sphere + disk' geometry Compton corona model provides a good description of Rossi X-ray Timing Explorer (RXTE) observations of the hard/low state of Cygnus X-1. Separately, we have analyzed the temporal data provided by RXTE. In this paper we consider the implications of this timing analysis for our best-fit 'sphere + disk' Comptonization models. We focus our attention on the observed Fourier frequency-dependent time delays between hard and soft photons. We consider whether the observed time delays are: created in the disk but are merely reprocessed by the corona; created by differences between the hard and soft photon diffusion times in coronae with extremely large radii; or are due to 'propagation' of disturbances through the corona. We find that the time delays are most likely created directly within the corona; however, it is currently uncertain which specific model is the most likely explanation. Models that posit a large coronal radius [or equivalently, a large Advection Dominated Accretion Flow (ADAF) region] do not fully address all the details of the observed spectrum. The Compton corona models that do address the full spectrum do not contain dynamical information. We show, however, that simple phenomenological propagation models for the observed time delays for these latter models imply extremely slow characteristic propagation speeds within the coronal region.

We have described a prereconstruction method for dual energy (PREDECT) analysis of CT scans. In theory, this method can (a) eliminate beam hardening and produce an accuracy comparable with monoenergetic scans and (b) provide the effective atomic number and electron density of any voxel scanned. Our implementation proves these statements and eliminates some of the objectionable noise. We constructed a phantom with a cylindrical sleeve-like compartment containing known amounts of high atomic number material simulating a removable skull. Conventional scans, with and without this beam hardener, were done of a water bath containing tubes of high electron and high atomic number material. Dual energy scans were then done for PREDECT. To increase the effective separation of the low and high energy beams by using more appropriate tube filtration, we fabricated a beam filter changer containing erbium, tungsten, aluminum, and steel. We used erbium, tungsten, and steel at high energy and aluminum, steel, and erbium at low energy for data acquisition. The reconstructions were compared visually and numerically for noise levels with the original steel only filtration. We found a decrease in noise down to approximately one-half the prior level when erbium/aluminum or tungsten/aluminum replaced the steel/steel filter. Erbium and tungsten were equally effective. Steel/erbium and steel/aluminum also significantly reduced image noise. The noise in the photoelectric (P) and Compton (C) images is negatively correlated. At any pixel, if the noise is positive in the P image, it is most probably negative in the C. Using this fact, the noise was reduced by postreconstruction processing.

RCH~V~AL COPY NATIONAL WAR COLLEGE "GENERAL PURPOSE GROUND FORCES" WHAT PURPOSE ?" LTC DAN CHALLIS 6 APRIL 1993 N A T I O N A L...06-04-1993 to 06-04-1993 4. TITLE AND SUBTITLE General Purpose Ground Forces: What Purpose ? 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...The ~Jarm glow of a much heralded Cold War victory, plus the Gulf War t:ciumph, the growth of democracy in developing countries, and the apparent

Dual Enrollment Engineering (DEEA) and Medical Science (DEMSA) Academies are two-year dual enrollment programs for high school students. Students explore engineering and medical careers through college coursework. Students prepare for higher education in engineering and medical fields while completing associate degrees in biology or engineering…

The cumulative all-sky survey by the Compton Gamma Ray Observatory (CGRO), composed of data acquired during the first three years of the mission, included a number of regions of very limited exposure. The most glaring deficiency in coverage was toward the region of the South Galactic Pole (SGP), which received significantly less exposure than other directions- by a factor of at least 2 to 3. Furthermore, nearly all of the SGP exposure was accumulated during the first year of the mission. Since blazars are known to be time-variable, and of unknown duty cycle, a pointing of the CCRO in that direction was considered highly desirable, and long overdue. In addition, data gathered from a pointing toward the SGP and its comparison with comprehensive data available for the North Galactic Pole would be extremely valuable to investigators studying the extragalactic diffuse emission. The reasons outlined above prompted our initiation of a Cycle 4 campaign to systematically search with EGRET and COMPTEL for gamma-ray emission from sources near the South Galactic Pole. The Cycle 4 SGP campaign consisted of tnvo 14-day observations separated in in time by approximately 10 months. The temporal separation of the observations was requested to allow a test for possible variations in the detected sources. Our primary targets were 38 FSRQs which lie within 30 degrees of the SGP, and which satisfy the basic criteria for candidate gamma-ray AGNs,flat-spectrum radio sources, many of which exhibit blazar-type properties). These targets were selected from the standard references, and from the available on-line databases (e.g., the NASA Extragalactic Database, NED), as the most promising AGN targets in the vicinity of the SGP. A 30 radius from the SGP was chosen as the boundary of our survey, since the selected targets would then fall within the most sensitive portion of the fields of view of EGRET and COMPTEL (i.e., within a 30 zenith angle), for a CGRO pointing directed exactly at the SGP

We present results of modelling the broad-band spectral energy distribution (SED) and multiwavelength variability of the bright flat spectrum radio quasars PKS 1510-089 with our time-dependent multizone Monte Carlo/Fokker-Planck code. As the primary source of seed photons for inverse Compton scattering, we consider radiation from the broad-line region (BLR), from the hot dust of the molecular torus and the local synchrotron radiation [synchrotron self-Compton (SSC)]. We evaluate the viability of different Compton models by comparing simulated multiwavelength light curves and SEDs with one of the best observed flares by PKS 1510-089, in 2009 March. The time dependence of our code and its correct handling of light travel time effects allow us to fully take into account the effect of the finite size of the active region, and in turn to fully exploit the information carried by time-resolved observed SEDs that are becoming increasingly available since the launch of Fermi. We confirm that the spectrum adopted for the external radiation field has an important impact on the modelling of the SED, in particular for the lower energy end of the Compton component which is observed in the X-ray band, which in turn is one of the most critical bands to assess the differences between external Compton and SSC emission. In the context of the scenario presented in this paper, where the flaring is caused by the increase of the number of relativistic electrons ascribed to the effect of the interaction of a portion of the jet (blob) with a shock, we cannot firmly discriminate the three main scenarios for γ-ray emission. However, results show clearly the differences produced by a more realistic treatment of the emitting source in the shape of SEDs and their time variability over relevant, observable time-scales, and demonstrate the crucial importance of time-dependent multizone models to advance our understanding of the physics of these sources, by taking full advantage of the wealth of

The Klein-Nishina differential cross section averaged over a relativistic Maxwellian electron distribution is analytically reduced to a single integral, which can then be rapidly evaluated in a variety of ways. A particularly fast method for numerically computing this single integral is presented. This is, to the authors' knowledge, the first correct computation of the Compton scattering kernel.

This letter from Compton to Fermi describes developments bearing on the establishment of site X (which, as of the letter date, is definitely determined as at the Tennessee Valley) for the construction of a pile and associated pilot plant buildings, describes the situation as of the letter date, and offers counsel as to how to proceed.

Compton reflection may be an important process in AGNs, since it provides an improvement over power-law fits to AGN spectra observed by Ginga and can also explain the spectrum of the cosmic X-ray background. The fraction of the total X-ray luminosity which is incident upon a thin steady alpha-disk if the X-rays are produced by inverse-Compton scattering of soft, disk photons off relativistic electrons located above the disk is calculated. This fraction is called the Compton reflection covering factor, f, and it is found that it can range between 0.5 and 0.88. This large range in f, due to a relativistic kinematic effect first calculated in this connection by Ghisellini et al (1991) is sufficient to explain the typical covering (about 0.5) observed in bright AGNs by Ginga as well as the large covering factor (about 0.9) required to explain the cosmic X-ray background in the Compton reflection model.

The inverse-Compton X-ray emission model for supernovae has been well established to explain the X-ray properties of many supernovae for over 30 years. However, no observational case has yet been found to connect the X-rays with the optical lights as they should be. Here, we report the discovery of a hard X-ray source that is associated with a Type II-b supernova. Simultaneous emission enhancements have been found in both the X-ray and optical light curves twenty days after the supernova explosion. While the enhanced X-rays are likely dominated by inverse-Compton scatterings of the supernova's lights from the Type II-b secondary peak, we propose a scenario of a high-speed supernova ejecta colliding with a low-density pre-supernova stellar wind that produces an optically thin and high-temperature electron gas for the Comptonization. The inferred stellar wind mass-loss rate is consistent with that of the supernova progenitor candidate as a yellow supergiant detected by the Hubble Space Telescope, providing an independent proof for the progenitor. This is also new evidence of the inverse-Compton emission during the early phase of a supernova.

The method of the Laser-Compton cooling of the electron beams is studied. Using a Monte Carlo code, we have evaluated the effects of the Laser-electron interaction for cooling. The optics with and without chromatic correction for cooling are examined. Problems of the optics for cooling are discussed.

Recently various laser-chirping schemes have been investigated with the goal of reducing or eliminating ponderomotive line broadening in Compton or Thomson scattering occurring at high laser intensities. As a next level of detail in the spectrum calculations, we have calculated the line smoothing and broadening expected due to incident beam energy spread within a one-dimensional plane wave model for the incident laser pulse, both for compensated (chirped) and unchirped cases. The scattered compensated distributions are treatable analytically within three models for the envelope of the incident laser pulses: Gaussian, Lorentzian, or hyperbolic secant. We use the new results to demonstrate that the laser chirping in Compton sources at high laser intensities: (i) enables the use of higher order harmonics, thereby reducing the required electron beam energies; and (ii) increases the photon yield in a small frequency band beyond that possible with the fundamental without chirping. This combination of chirping and higher harmonics can lead to substantial savings in the design, construction and operational costs of the new Compton sources. This is of particular importance to the widely popular laser-plasma accelerator based Compton sources, as the improvement in their beam quality enters the regime where chirping is most effective.

Comparison of grades awarded to all students in all courses at SUNY Geneseo in Spring 1990 and Spring 2000 shows a significant overall increase and a fairly stable pattern of grading practices across departments that resembles the pattern reported by Compton and Metheny in 2000 and other investigators.

A green laser (CW, 532 nm) based Fabry-Perot cavity for high precision Compton Polarimetry is under development in Hall A of the Jefferson Laboratory. In this paper, we present the principle and the preliminary studies for our test cavity.

An analysis is made of the role of the kinematic constraint in obtaining a dispersion inequality for the Compton effect on the nucleon in the approach in which use is made of the t-channel helicity amplitudes. It is shown that the most restrictive (optimal) inequality can be obtained without allowance for the kinematic constraint at the point t = 0.

Characterization and interpretation of flat ancient material objects, such as those found in archaeology, paleoenvironments, paleontology, and cultural heritage, have remained a challenging task to perform by means of conventional x-ray tomography methods due to their anisotropic morphology and flattened geometry. To overcome the limitations of the mentioned methodologies for such samples, an imaging modality based on Compton scattering is proposed in this work. Classical x-ray tomography treats Compton scattering data as noise in the image formation process, while in Compton scattering tomography the conditions are set such that Compton data become the principal image contrasting agent. Under these conditions, we are able, first, to avoid relative rotations between the sample and the imaging setup, and second, to obtain three-dimensional data even when the object is supported by a dense material by exploiting backscattered photons. Mathematically this problem is addressed by means of a conical Radon transform and its inversion. The image formation process and object reconstruction model are presented. The feasibility of this methodology is supported by numerical simulations.

This paper discusses the possibility of using Compton scattering – an inelastic X-ray scattering process that yields a projection of the electron momentum density – to probe magnetoelectrical properties. It is shown that an antisymmetric component of the momentum density is a unique fingerprint of such time- and parity-odd physics. It is argued that polar ferromagnets are ideal candidates to demonstrate this phenomenon and the first experimental results are shown, on a single-domain crystal of GaFeO3. The measured antisymmetric Compton profile is very small (≃ 10−5 of the symmetric part) and of the same order of magnitude as the statistical errors. Relativistic first-principles simulations of the antisymmetric Compton profile are presented and it is shown that, while the effect is indeed predicted by theory, and scales with the size of the valence spin–orbit interaction, its magnitude is significantly overestimated. The paper outlines some important constraints on the properties of the antisymmetric Compton profile arising from the underlying crystallographic symmetry of the sample. PMID:26919371

Gamma-ray spectroscopy provides a wealth of information about accelerated particles in solar flares, as well as the ambient medium with which these energetic particles interact. The neutron capture line (2.223 MeV), the strongest in the solar gamma-ray spectrum, forms in the deep atmosphere. The energy of these photons can be reduced via Compton scattering. With the fully relativistic GEANT4 toolkit, we have carried out Monte Carlo simulations of the transport of a neutron capture line in solar flares, and applied them to the flare that occurred on 2005 January 20 (X7.1/2B), one of the most powerful gamma-ray flares observed by RHESSI during the 23rd solar cycle. By comparing the fitting results of different models with and without Compton scattering of the neutron capture line, we find that when including the Compton scattering for the neutron capture line, the observed gamma-ray spectrum can be reproduced by a population of accelerated particles with a very hard spectrum (s <= 2.3). The Compton effect of a 2.223 MeV line on the spectra is therefore proven to be significant, which influences the time evolution of the neutron capture line flux as well. The study also suggests that the mean vertical depth for neutron capture in hydrogen for this event is about 8 g cm-2.

The inverse-Compton X-ray emission model for supernovae has been well established to explain the X-ray properties of many supernovae for over 30 years. However, no observational case has yet been found to connect the X-rays with the optical lights as they should be. Here, we report the discovery of a hard X-ray source that is associated with a Type II-b supernova. Simultaneous emission enhancements have been found in both the X-ray and optical light curves twenty days after the supernova explosion. While the enhanced X-rays are likely dominated by inverse-Compton scatterings of the supernova’s lights from the Type II-b secondary peak, we propose a scenario of a high-speed supernova ejecta colliding with a low-density pre-supernova stellar wind that produces an optically thin and high-temperature electron gas for the Comptonization. The inferred stellar wind mass-loss rate is consistent with that of the supernova progenitor candidate as a yellow supergiant detected by the Hubble Space Telescope, providing an independent proof for the progenitor. This is also new evidence of the inverse-Compton emission during the early phase of a supernova. PMID:27481538

Describes an experiment to verify the Compton collision formula and the angular dependance of the Klein-Nishina formula. Equipment used is a 1-mCi(137)Cs source, 2x2 in. NaI detector and a multichannel analyzer. Suitable for honor undergraduates. (Author/GA)

We present a study on the effects of detector material, radionuclide source and source position on the Compton camera aimed at realistic characterization of the camera's performance in multitracer imaging as it relates to brain imaging. The GEANT4 Monte Carlo simulation software was used to model the physics of radiation transport and interactions with matter. Silicon (Si) and germanium (Ge) detectors were evaluated for the scatterer, and cadmium zinc telluride (CZT) and cerium-doped lanthanum bromide (LaBr(3):Ce) were considered for the absorber. Image quality analyses suggest that the use of Si as the scatterer and CZT as the absorber would be preferred. Nevertheless, two simulated Compton camera models (Si/CZT and Si/LaBr(3):Ce Compton cameras) that are considered in this study demonstrated good capabilities for multitracer imaging in that four radiotracers within the nuclear medicine energy range are clearly visualized by the cameras. It is found however that beyond a range difference of about 2 cm for (113m)In and (18)F radiotracers in a brain phantom, there may be a need to rotate the Compton camera for efficient brain imaging.

Recent analyses of multiwavelength light curves of gamma-ray bursts afterglows point to values of the magnetic turbulence well below the canonical ˜1 per cent of equipartition, in agreement with theoretical expectations of a microturbulence generated in the shock precursor, which then decays downstream of the shock front through collisionless damping. As a direct consequence, the Compton parameter Y can take large values in the blast. In the presence of decaying microturbulence and/or as a result of the Klein-Nishina suppression of inverse Compton cooling, the Y parameter carries a non-trivial dependence on the electron Lorentz factor, which modifies the spectral shape of the synchrotron and inverse Compton components. This paper provides detailed calculations of this synchrotron self-Compton spectrum in this large Y regime, accounting for the possibility of decaying microturbulence. It calculates the expected temporal and spectral indices α and β customarily defined by F_ν ∝ t_obs^{-α }ν ^{-β } in various spectral domains. This paper also makes predictions for the very high energy photon flux; in particular, it shows that the large Y regime would imply a detection rate of gamma-ray bursts at >10 GeV several times larger than currently anticipated.

We discuss the{gamma}-ray production by Compton backscattering of intracavity storage ring Free-Electron Laser radiation. We use a semi-analytical model which provides the build up of the signal combined with the storage ring damping mechanism and derive simple relations yielding the connection between backscattered. Photons brightness and the intercavity laser equilibrium intensity.

The purpose of this Delphi study was to determine the essential components of dual credit in New Mexico. Dual credit experts from colleges and high schools in New Mexico were asked to participate in a three-round Delphi study to determine what the future policy of dual credit should be, and why it should be that way. Definitions of dual credit may…

Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

In a conventional PET scanner, coincidence events are measured with a limited energy window for detection of photoelectric events in order to reject Compton scatter events that occur in a patient, but Compton scatter events caused in detector crystals are also rejected. Scatter events within the patient causes scatter coincidences, but inter crystal scattering (ICS) events have useful information for determining an activity distribution. Some researchers have reported the feasibility of PET scanners based on a Compton camera for tracing ICS into the detector. However, these scanners require expensive semiconductor detectors for high-energy resolution. In the Anger-type block detector, single photons interacting with multiple detectors can be obtained for each interacting position and complete information can be gotten just as for photoelectric events in the single detector. ICS events in the single detector have been used to get coincidence, but single photons interacting with multiple detectors have not been used to get coincidence. In this work, we evaluated effect of sensitivity improvement using Compton kinetics in several types of DOI-PET scanners. The proposed method promises to improve the sensitivity using coincidence events of single photons interacting with multiple detectors, which are identified as the first interaction (FI). FI estimation accuracy can be improved to determine FI validity from the correlation between Compton scatter angles calculated on the coincidence line-of-response. We simulated an animal PET scanner consisting of 42 detectors. Each detector block consists of three types of scintillator crystals (LSO, GSO and GAGG). After the simulation, coincidence events are added as information for several depth-of-interaction (DOI) resolutions. From the simulation results, we concluded the proposed method promises to improve the sensitivity considerably when effective atomic number of a scintillator is low. Also, we showed that FI estimate

The intra-cluster medium of several galaxy clusters hosts large-scale regions of diffuse synchrotron radio emission, known as radio halos and relics, which demonstrates the presence of magnetic fields and relativistic electrons in clusters. These relativistic electrons should also emit X-rays through inverse-Compton scattering off of cosmic microwave background photons. The detection of such a non-thermal X-ray component, together with the radio measurement, would permit the magnetic field to be clearly separated from the relativistic electron distribution because the inverse-Compton emission is independent of the magnetic field in the cluster. However, non-thermal X-rays have not been conclusively detected from any cluster of galaxies so far. In this paper, for the first time, we model the synchrotron and inverse-Compton emission of all clusters hosting radio halos and relics for which the spectral index can be determined. We provide constraints on the volume-average magnetic field by comparing with current X-ray measurements. We then estimate the maximum volume-average magnetic field that will allow detection of inverse-Compton hard X-rays by the ASTRO-H satellite. We find that several clusters are good targets for ASTRO-H to detect their inverse-Compton emission, in particular for what corresponds to radio relics, so we propose a list of promising targets for which ASTRO-H can test ≥ 1μG magnetic fields. We conclude that the already operating NuSTAR and the soon-to-be-launched ASTRO-H definitely have the potential of shedding light on the long-sought non-thermal hard-X-ray emission in clusters of galaxies. Appendix A is available in electronic form at http://www.aanda.org

We are currently developing a compact monochromatic X-ray source based on laser-electron Compton scattering for the purpose of medical applications at the University of Tokyo. To realize remarkably compact-, high-intensity- and highly stable system, we adopt an X-band (11.424 GHz) multi-bunch linear accelerator (linac) and reliable Q-switch Nd:YAG laser. The injector of the system consists of a 3.5-cell X-band thermionic cathode RF-gun and an alpha magnet. So far, we have continued high-power experiment and beam generation on X-band thermionic cathode RF-gun. However, breakdown was frequently occurred at coaxial structure around the thermionic cathode. In order to resolve the breakdown, we adopt a choke structure around the thermionic cathode. In this paper, the details of Compton scattering X-ray source the University of Tokyo, the experimental results of the X-ray generation, and upgrade of the X-band thermionic cathode RF-gun will be presented.

The use of dual credit has been expanding rapidly. Dual credit is a college course taken by a high school student for which both college and high school credit is given. Previous studies provided limited quantitative evidence that dual credit/dual enrollment is directly connected to positive student outcomes. In this study, predictive statistics…

Purpose: The purpose of this investigation was to determine the extent to which differences were present in dual credit course enrollment. Specifically examined were whether differences were present in the first semester GPA and at the end of the first two semesters for students who enrolled in dual credit courses while in high school from…

A bifocal dual reflector antenna is similar to and has better scan capability than classical cassegrain reflector antenna. The method used in determining the reflector surfaces is a modification of a design method for the dielectric bifocal lens. The three dimensional dual reflector is obtained by first designing an exact (in geometrical optics sense) two-point corrected two dimensional reflector and then rotating it around its axis of symmetry. A point by point technique is used in computing the reflector surfaces. Computed radiation characteristics of the dual reflector are compared with those of a cassegrain reflector. The results confirm that the bifocal antenna has superior performance.

We present a model in which the GRB prompt emission at E E(sub peak) is due to bulk Comptonization by the relativistic blast wave motion of either its own synchrotron photons of ambient photons of the stellar configuration that gave birth to the GRB. The bulk Comptonization process then induces the production of relativistic electrons of Lorentz factor equal to that of the blast wave through interactions with its ambient protons. The inverse compton emission of these electrons produces a power law component that extends to multi GeV energies in good agreement with the LAT GRB observations.

Purpose: For accurate tissue inhomogeneity correction in radiotherapy treatment planning, the author previously proposed a simple conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide ρ{sub e} range. The purpose of the present study was to reveal the relation between the ΔHU image for ρ{sub e} calibration and a virtually monochromatic CT image by performing numerical analyses based on the basis material decomposition in dual-energy CT. Methods: The author determined the weighting factor, α{sub 0}, of the ΔHU–ρ{sub e} conversion through numerical analyses of the International Commission on Radiation Units and Measurements Report-46 human body tissues using their attenuation coefficients and given ρ{sub e} values. Another weighting factor, α(E), for synthesizing a virtual monochromatic CT image from high- and low-kV CT images, was also calculated in the energy range of 0.03 < E < 5 MeV, assuming that cortical bone and water were the basis materials. The mass attenuation coefficients for these materials were obtained using the XCOM photon cross sections database. The effective x-ray energies used to calculate the attenuation were chosen to imitate a dual-source CT scanner operated at 80–140 and 100–140 kV/Sn. Results: The determined α{sub 0} values were 0.455 for 80–140 kV/Sn and 0.743 for 100–140 kV/Sn. These values coincided almost perfectly with the respective maximal points of the calculated α(E) curves located at approximately 1 MeV, in which the photon-matter interaction in human body tissues is exclusively the incoherent (Compton) scattering. Conclusions: The ΔHU image could be regarded substantially as a CT image acquired with monoenergetic 1-MeV photons, which provides a linear relationship between CT numbers and electron densities.

The spatial distributions of bone and soft tissue in human body are separated by independent component analysis (ICA) of dual-energy x-ray images. It is because of the dual energy imaging modelí-s conformity to the ICA model that we can apply this method: (1) the absorption in body is mainly caused by photoelectric absorption and Compton scattering; (2) they take place simultaneously but are mutually independent; and (3) for monochromatic x-ray sources the total attenuation is achieved by linear combination of these two absorption. Compared with the conventional method, the proposed one needs no priori information about the accurate x-ray energy magnitude for imaging, while the results of the separation agree well with the conventional one.

There has been an upsurge in interest in Compton Scattering experiments as a means to understand the internal structure and dynamics of the nucleon. The new PDG value of β, the proton magnetic polarizability, changed noticeably, with no new data, simply new theoretical treatment of the existing data set. This indicates that the existing data is insufficient to constrain our extraction of these fundamental constants, which are important in areas of physics such as the proton radius determination, and neutron star physics. In the A2 Collaboration of the Institut fuer Kernphysik in Mainz, we use the MAMI accelerator with the Glasgow Mainz Photon Tagger to produce a quasi-monoenergetic, linearly polarized photon beam and apply it to a liquid hydrogen target. The reaction products detected in the Crystal Ball and TAPS large acceptance spectrometer array allow clean separation of the low-cross-section hadronic Compton scattering process. In so doing, we have produced the firs t measurement of the photon asymmetry in Compton scattering on the proton below the pion production threshold. Preliminary results show a demonstrable effect due to the polarizabilities. We will cover the experimental results and future prospects of the A2 polarizability program. There has been an upsurge in interest in Compton Scattering experiments as a means to understand the internal structure and dynamics of the nucleon. The new PDG value of β, the proton magnetic polarizability, changed noticeably, with no new data, simply new theoretical treatment of the existing data set. This indicates that the existing data is insufficient to constrain our extraction of these fundamental constants, which are important in areas of physics such as the proton radius determination, and neutron star physics. In the A2 Collaboration of the Institut fuer Kernphysik in Mainz, we use the MAMI accelerator with the Glasgow Mainz Photon Tagger to produce a quasi-monoenergetic, linearly polarized photon beam and

X-ray fluorescence imaging is a promising imaging technique able to depict the spatial distributions of low amounts of molecular agents in vivo. Currently, the translation of the technique to preclinical and clinical applications is hindered by long scanning times as objects are scanned with flux-limited narrow pencil beams. The study presents a novel imaging approach combining x-ray fluorescence imaging with Compton imaging. Compton cameras leverage the imaging performance of XFCT and abolish the need for pencil beam excitation. The study examines the potential of this new imaging approach on the base of Monte-Carlo simulations. In the work, it is first presented that the particular option of slice/fan-beam x-ray excitation has advantages in image reconstruction in regard of processing time and image quality compared to traditional volumetric Compton imaging. In a second experiment, the feasibility of the approach for clinical applications with tracer agents made from gold nano-particles is examined in a simulated lung scan scenario. The high energy of characteristic x-ray photons from gold is advantageous for deep tissue penetration and has lower angular blurring in the Compton camera. It is found that Doppler broadening in the first detector stage of the Compton camera adds the largest contribution on the angular blurring; physically limiting the spatial resolution. Following the analysis of the results from the spatial resolution test, resolutions in the order of one centimeter are achievable with the approach in the center of the lung. The concept of Compton imaging allows one to distinguish to some extent between scattered photons and x-ray fluorescent photons based on their difference in emission position. The results predict that molecular sensitivities down to 240 pM l-1 for 5 mm diameter lesions at 15 mGy for 50 nm diameter gold nano-particles are achievable. A 45-fold speed up time for data acquisition compared to traditional pencil beam XFCT could

Focuses on languages for specific purposes, providing a brief historical perspective, examining it as a profession, discipline, or neither; its role in science and law; language for business purposes; and the position of English worldwide. (Author/VWL)

CoDeX (Compton-imaging Detector in Xenon) is an R&D Compton gamma-ray imaging detector that uses 30 kg of xenon in a two-phase time projection chamber. Time projection relative to the initial scintillation signal provides the vertical interaction positions, and either PMT-sensed gas electroluminescence or a charge-sensitive amplifier quantifies the drifted ionization signal. Detector features to enable Compton imaging are a pair of instrumented wire grids added to sense the horizontal position of clouds of drifted electrons that traverse the detector. Each wire is individually amplified in the cold xenon environment. Design choices addressing the thermodynamic and xenon purity constraints of this system will be discussed. We will also discuss the mechanical designs, engineering challenges, and performance of this Compton-imaging detector.

We measured photoneutron cross sections for {sup 197}Au with quasi-monochromatic laser inverse-Compton scattering gamma rays. We present results of the measurement in comparison with the existing data.

Background/Context: The evolution of validity understandings from mid-century to now has emphasized that test validity depends on test purpose--adding consequence considerations to issues of interpretation and evidentiary warrants. Purpose: To consider the tensions created by multiple purposes for assessment and sketch briefly how we got to where…

"Purpose" is an important term in rhetorical theory and writing pedagogy. An analysis of the presentation of "purpose" in three well-regarded, theory-based textbooks ("Writing in the Liberal Arts Tradition: A Rhetoric with Readings,""Writing with a Purpose," and "Form and Surprise in Composition")…

In the field of nuclear medicine, nuclear security and astrophysics, Compton imaging is a promising technique for gamma-ray source imaging. We are developing a Compton imager using two layers of CdZnTe pixel array detectors. In this paper, the backward-scattering effect within such imagers is numerically studied using Geant4 Monte Carlo Package. From images reconstructed based on forward-scattering and backward-scattering imaging events, the imaging precision was investigated in a comparative analysis, in regard to energy resolution and position resolution. Furthermore, to establish a method to use backward-scattering imaging events properly so that the imaging efficiency can be significantly improved, the difference between reconstruction from forward-scattering and backward-scattering imaging events was analyzed to uncover a causal mechanism.

We have performed a novel comparison between electron-beam polarimeters based on Møller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (< 5 μA) during the Qweak experiment in Hall-C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 μA) operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Møller measurements made at low beam currents to physics experiments performed at higher beam currents. The agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.

An important diagnostic tool for inertial confinement fusion is time-resolved imaging of the dense cold fuel surrounding the hot spot. Here we report on the source and diagnostic development of hard x-ray radiography and on the first radiographs of direct drive implosions obtained at photon energies up to about 100keV, where the Compton effect is the dominant contributor to the shell opacity. The radiographs of direct drive, plastic shell implosions obtained at the OMEGA laser facility have a spatial resolution of {approx}10um and a temporal resolution of {approx}10ps. This novel Compton Radiography is an invaluable diagnostic tool for Inertial Confinement Fusion targets, and will be integrated at the National Ignition Facility (NIF).

Swift, Chandra, and XMM have found a weak but nearly constant X-ray component from Swift J1644+57 that appeared at ∼500 days and was visible at least until ∼1400 days after the stellar capture, which cannot be explained by standard tidal disruption theories. We suggest that this X-ray afterglow component may result from the Thomson scattering between the primary X-rays and its surrounding plasma, i.e., a Compton echo effect. Similar phenomena have also been observed from molecular clouds in our Galactic Center, which were caused by the past activity of Srg A*. If this interpretation of Swift J1644+57 afterglow is correct, this is the first Compton Echo effect observed in the cosmological distances.

In this paper, we report the experimental Compton profile (CP) of TiB{sub 2} using high energy {sup 137}Cs γ-rays Compton spectrometer. To interpret the experimental momentum density, we have calculated the CPs using Hartree-Fock (HF), density functional theory (DFT) and hybridization of DFT and HF within linear combination of atomic orbitals. The theoretical profile with generalized gradient approximation is found to be relatively in better agreement with the experimental profile. A sharp valley in density of states and hence the pseudogap near the Fermi energy is attributed to hybridization of Ti-3d and B-2p states and almost reverse trend of energy bands below and above the Fermi energy.

We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article.

We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article.

Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θcmp=70 ° . The longitudinal transfer KLL, measured to be 0.645 ±0.059 ±0.048 , where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ˜3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

X-ray generation based on laser-electron Compton scattering is one attractive method to achieve a compact laboratory-sized high-brightness x-ray source. We have designed, built, and tested such a source; it combines a 50 MeV multibunch electron linac with a mode-locked 1064 nm laser stored and amplified in a Fabry-Perot optical cavity. We directly observed trains of pulsed x rays using a microchannel plate detector; the resultant yield was found to be 1.2x10{sup 5} Hz in good agreement with prediction. We believe that the result has demonstrated good feasibility of linac-based compact x-ray sources via laser-electron Compton scatterings.

Previous studies of the active galactic nuclei (AGNs) contribution to the cosmic X-ray background (CXB) consider only observable parameters such as luminosity and absorbing column. Here, for the first time, we extend the study of the CXB to physical parameters including the Eddington ratio of the sources and the black hole mass. In order to calculate the contribution to the CXB of AGN accreting at various Eddington ratios, an evolving Eddington ratio space density model is calculated. In particular, Compton thick (CT) AGNs are modeled as accreting at specific, physically motivated Eddington ratios instead of as a simple extension of the Compton thin type 2 AGN population. Comparing against the observed CT AGN space densities and log N-log S relation indicates that CT AGNs are likely a composite population of AGNs made up of sources accreting either at >90% or <1% of their Eddington rate.

Highly-collimated, polarized, mono-energetic beams of tunable gamma-rays may be created via the optimized Compton scattering of pulsed lasers off of ultra-bright, relativistic electron beams. Above 2 MeV, the peak brilliance of such sources can exceed that of the world's largest synchrotrons by more than 15 orders of magnitude and can enable for the first time the efficient pursuit of nuclear science and applications with photon beams, i.e. Nuclear Photonics. Potential applications are numerous and include isotope-specific nuclear materials management, element-specific medical radiography and radiology, non-destructive, isotope-specific, material assay and imaging, precision spectroscopy of nuclear resonances and photon-induced fission. This review covers activities at the Lawrence Livermore National Laboratory related to the design and optimization of mono-energetic, laser-Compton gamma-ray systems and introduces isotope-specific nuclear materials detection and assay applications enabled by them.

The processes of the nonlinear Compton and the nonlinear Thomson scattering in a field of intense plane electromagnetic wave in terms of photon yield have been considered. The quantum consideration of the Compton scattering process allows us to calculate the probability of a few successive collisions k of an electron with laser photons accompanied by the absorption of n photons (nonlinear regime) when the number of collisions and the number of absorbed photons are of random quantities. The photon spectrum of the nonlinear Thomson scattering process was obtained from the classical formula for intensity using the Planck's law. The conditions for which the difference between the classical and the quantum regimes is manifested was obtained. Such a condition is determined by a discrete quantum radiation mechanism, namely, by the mean number of photons k bar emitted by an electron passing through the laser pulse.

In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

Multi-energy gamma-ray fields have been imaged with a ring Compton scatter camera (RCC). The RCC is intended for industrial applications, where there is a need to image multiple gamma-ray lines from spatially extended sources. To our knowledge, the ability of a Compton scatter camera to perform this task had not previously been demonstrated. Gamma rays with different incident energies are distinguished based on the total energy deposited in the camera elements. For multiple gamma-ray lines, separate images are generated for each line energy. Random coincidences and other interfering interactions have been investigated. Camera response has been characterized for energies from 0.511 to 2.75 MeV. Different gamma-ray lines from extended sources have been measured and images reconstructed using both direct and iterative algorithms.

A framework is developed for the accurate calculation of Compton and synchrotron processes in a special class of spherically-symmetric sources. The models considered take a distribution in magnetic field values and high-energy electron density that varies smoothly from central values to values at the outer boundary of the source. Further, the assumption is made that the magnetic field has local disorder (isotropy) and the high-energy electron distribution has local isotropy. Then, in terms of parameters of the source, the synchrotron brightness distribution, total synchrotron flux, Compton-synchrotron flux, and synchrotron self-absorption turnover are all computed accurately. Results are given with a view toward application to the analysis of compact non-thermal sources.

We discuss the application of an effective field theory (EFT) which incorporates the chiral symmetry of QCD to Compton scattering from the proton and deuteron. We describe the chiral EFT analysis of the γp scattering database presented in our recent review [1], which gives: αE1(p) = 10.5±0.5(stat)±0.8(theory), βM1(p) = 2.7±0.5(stat)±0.8(theory), for the electric and magnetic dipole polarizability of the proton.We also summarize Ref. [1]'s chiral EFT analysis of the world data on coherent Compton scattering from deuterium, which yields: αE1(s) = 10.5±2.0(stat)±0.8(theory), βM1(s) = 3.6±1.0(stat)±0.8(theory).

A new Compton polarimeter is built on the CEBAF Hall A electron beam line. Performances of 10% resolution and 1% calibration are required for the photon calorimeter of this polarimeter. This calorimeter is built with lead tungstate scintillators coming from the CMS electromagnetic calorimeter R&D. Beam tests of this detector have been made using the tagged photon beam line at MAMI, Mainz, and a resolution of 1.76%+2.75%/v+0.41%/E has been measured.

We present a simple and versatile polarimeter for x rays in the energy range of 10-30 keV. It uses Compton scattering in low-Z materials such as beryllium or boron carbide. The azimuthal distribution of the scattered x rays is sampled by an array of 12 silicon PIN diodes operated at room temperature. We evaluated the polarimetry performance using Monte-Carlo simulations and show experimental results.

A Compton telescope for dose monitoring in hadron therapy is under development at IFIC-Valencia. The system consists of three layers of LaBr{sub 3} crystals coupled to silicon photomultiplier arrays. Two- and three-layer versions of the device have been tested in the laboratory. Images of Na-22 sources have been reconstructed. In addition, the two-layer version has been tested in a proton beam. Performance improvement and full characterization of the device are ongoing. (authors)

The role of intershell correlations in nonresonant Compton scattering of an X-ray photon by a free multielectron atom is studied theoretically for the Ar atom. The results of calculation are of a predictive nature. The developed mathematical formalism is general in nature and can be applied to a wide set of elements from the Periodic Table, for which the description of the wavefunctions of scattering states in the nonrelativistic Hartree-Fock approximation remains correct.

Pulsar wind driven synchrotron nebulae are offering a unique view on the connection of the pulsar wind and the surrounding medium. The Crab nebula is particu- larly well suited for detailed studies of the different emis- sion regions. As inferred from the observed synchrotron emission extending beyond MeV energies, the Crab is a unique and extreme accelerator. In the framework of the synchrotron/inverse Compton emission model, the same electrons with energies exceeding 1015 eV that are re- sponsible for the MeV synchrotron emission produce via inverse Compton scattering 10-50 TeV radiation which has recently been observed with the HEGRA system of ground based gamma-ray telescopes. Here we discuss the close relation of the two energy bands covered by INTE- GRAL and ground based gamma-ray telescopes. Despite the lack of sufficient spatial resolution in both bands to resolve the emission region, correlation of the flux mea- surements in the two energy bands would allow to con- strain the structure of the emission region. The emission region is expected to be a very compact region (limited by the life-time of the electrons) near the termination shock of the pulsar wind. We extend previous model calcula- tions for the nebula's emission to include an additional compact non-thermal emission region recently detected at mm wavelengths. The overall good agreement of this model with data constrains additional emission processes (ions in the wind, inverse Compton from the unshocked wind) to be of little relevance. Key words: Crab nebula; acceleration; Crab pulsar; elec- trons; radiation; synchrotron; inverse Compton.

We present a simple and versatile polarimeter for x rays in the energy range of 10–30 keV. It uses Compton scattering in low-Z materials such as beryllium or boron carbide. The azimuthal distribution of the scattered x rays is sampled by an array of 12 silicon PIN diodes operated at room temperature. We evaluated the polarimetry performance using Monte-Carlo simulations and show experimental results.

We perform a stability analysis of a Monte Carlo method for simulating the Compton scattering of photons by free electron in high energy density applications and develop time-step limits that avoid unstable and oscillatory solutions. Implementing this Monte Carlo technique in multi physics problems typically requires evaluating the material temperature at its beginning-of-time-step value, which can lead to this undesirable behavior. With a set of numerical examples, we demonstrate the efficacy of our time-step limits.

A Monte Carlo approach was used to study the effects of Doppler energy broadening on Compton camera performance. The GEANT4 simulation toolkit was used to model the radiation transport and interactions with matter in a simulated Compton camera. The low energy electromagnetic physics model of GEANT4 incorporating Doppler broadening developed by Longo et al. was used in the simulations. The camera had a 9 × 9 cm scatterer and a 10 × 10 cm absorber with a scatterer to-absorber separation of 5 cm. Modelling was done such that only the effects of Doppler broadening were taken into consideration and effects of scatterer and absorber thickness and pixelation were not taken into account, thus a 'perfect' Compton camera was assumed. Scatterer materials were either silicon or germanium and the absorber material was cadmium zinc telluride. Simulations were done for point sources 10 cm in front of the scatterer. The results of the simulations validated the use of the low energy model of GEANT4. As expected, Doppler broadening was found to degrade the Compton camera imaging resolution. For a 140.5 keV source the resulting full-width-at-half-maximum (FWHM) of the point source image without accounting for Doppler broadening and using a silicon scatterer was 0.58 mm. This degraded to 7.1 mm when Doppler broadening was introduced and degraded further to 12.3 mm when a germanium scatterer was used instead of silicon. But for a 511 keV source, the FWHM was better than for a 140 keV source. The FWHM improved to 2.4 mm for a silicon scatterer and 4.6 mm for a germanium scatterer. Our result for silicon at 140.5 keV is in very good agreement with that published by An et al.

Development of a Compton camera for low energy medical imaging applications is underway. The ProSPECTus project aims to utilize position sensitive detectors to generate high quality images using electronic collimation. This method has the potential to significantly increase the imaging efficiency compared with mechanically collimated SPECT systems, a highly desirable improvement on clinical systems. Design considerations encompass the geometrical optimisation and evaluation of image quality from the system which is to be built and assessed.

Correct computation of the Compton scattering kernel (CSK), defined to be the Klein-Nishina differential cross section averaged over a relativistic Maxwellian electron distribution, is reported. The CSK is analytically reduced to a single integral, which can then be rapidly evaluated using a power series expansion, asymptotic series, and rational approximation for sigma(s). The CSK calculation has application to production codes that aim at understanding certain astrophysical, laser fusion, and nuclear weapons effects phenomena.

The Arthur Holly Compton Gamma Ray observatory is the second in NASA's series of Great Observatories. It has been in operation for over three years, and has given a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments continue to function nearly flawlessly, and many significant discoveries have been made. The authors describe the capabilities of the four scientific instruments, and highlight some of the results from the first three years of the mission.

We study the energy dependent photon variability from a thermal Comptonizing plasma that is oscillating at kHz frequencies. In particular, we solve the linearized time-dependent Kompaneets equation and consider the oscillatory perturbation to be either in the soft photon source or in the heating rate of the plasma. For each case, we self consistently consider the energy balance of the plasma and the soft photon source. The model incorporates the possibility of a fraction of the Comptonized photons impinging back into the soft photon source. We find that when the oscillation is due to the soft photon source, the variation of the fractional root mean sqaure (rms) is nearly constant with energy and the time-lags are hard. However, for the case when the oscillation is due to variation in the heating rate of the corona, and when a significant fraction of the photons impinge back into the soft photon source, the rms increases with energy and the time-lags are soft. As an example, we compare the results with the ˜850 Hz oscillation observed on 1996 March 3 for 4U 1608-52 and show that both the observed soft time-lags as well as the rms versus energy can be well described by such a model where the size of the Comptonizing plasma is ˜1 km. Thus, modelling of the time-lags as due to Comptonization delays, can provide tight constraints on the size and geometry of the system. Detailed analysis would require well-constrained spectral parameters.

A Compton telescope for dose monitoring in hadron therapy is under development at IFIC. The system consists of three layers of LaBr3 crystals coupled to silicon photomultiplier arrays. (22)Na sources have been successfully imaged reconstructing the data with an ML-EM code. Calibration and temperature stabilization are necessary for the prototype operation at low coincidence rates. A spatial resolution of 7.8 mm FWHM has been obtained in the first imaging tests.

A Compton telescope for dose monitoring in hadron therapy is under development at IFIC. The system consists of three layers of LaBr3 crystals coupled to silicon photomultiplier arrays. 22Na sources have been successfully imaged reconstructing the data with an ML-EM code. Calibration and temperature stabilization are necessary for the prototype operation at low coincidence rates. A spatial resolution of 7.8 mm FWHM has been obtained in the first imaging tests. PMID:26870693

We describe Hybrid Evaluator for Radiative Objects Including Comptonization (HEROIC), an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models Comptonization via the Kompaneets equation, using a quadratic approximation for the source function in a short characteristics radiation solver. It employs a simple form of accelerated lambda iteration to handle regions of high scattering opacity. In addition to solving for the radiation field, HEROIC also solves for the gas temperature by applying the condition of radiative equilibrium. We present benchmarks and tests of the Comptonization module in HEROIC with simple 1D and 3D scattering problems. We also test the ability of the code to handle various relativistic effects using model atmospheres and accretion flows in a black hole space-time. We present two applications of HEROIC to general relativistic magnetohydrodynamics simulations of accretion discs. One application is to a thin accretion disc around a black hole. We find that the gas below the photosphere in the multidimensional HEROIC solution is nearly isothermal, quite different from previous solutions based on 1D plane parallel atmospheres. The second application is to a geometrically thick radiation-dominated accretion disc accreting at 11 times the Eddington rate. Here, the multidimensional HEROIC solution shows that, for observers who are on axis and look down the polar funnel, the isotropic equivalent luminosity could be more than 10 times the Eddington limit, even though the spectrum might still look thermal and show no signs of relativistic beaming.

Gamma-ray imaging utilizing Compton scattering has traditionally relied on measuring coincident gamma-ray interactions to map directional information of the source distribution. This coincidence requirement makes it an inherently inefficient process. We present an approach to gamma-ray reconstruction from Compton scattering that requires only a single electron tracking detector, thus removing the coincidence requirement. From the Compton scattered electron momentum distribution, our algorithm analytically computes the incident photon's correlated direction and energy distributions. Because this method maps the source energy and location, it is useful in applications, where prior information about the source distribution is unknown. We demonstrate this method withmore » electron tracks measured in a scientific Si charge coupled device. While this method was demonstrated with electron tracks in a Si-based detector, it is applicable to any detector that can measure electron direction and energy, or equivalently the electron momentum. For example, it can increase the sensitivity to obtain energy and direction in gas-based systems that suffer from limited efficiency.« less

The Compton-Belkovich Volcanic Complex (CBVC) is a 25 × 35 km feature on the lunar farside marked by elevated topography, high albedo, high thorium concentration, and high silica content. Morphologies indicate that the complex is volcanic in origin and compositions indicate that it represents rare silicic volcanism on the Moon. Constraining the timing of silicic volcanism at the complex is necessary to better understand the development of evolved magmas and when they were active on the lunar surface. We employ image analysis and crater size-frequency distribution (CSFD) measurements on several locations within the complex and at surrounding impact craters, Hayn (87 km diameter), and Compton (160 km diameter), to determine relative and absolute model ages of regional events. Using CSFD measurements, we establish a chronology dating regional resurfacing events and the earliest possible onset of CBVC volcanism at ∼3.8 Ga, the formation of Compton Crater at 3.6 Ga, likely resurfacing by volcanism at the CBVC at ∼3.5 Ga, and the formation of Hayn Crater at ∼1 Ga. For the CBVC, we find the most consistent results are obtained using craters larger than 300 m in diameter; the small crater population is affected by their approach to an equilibrium condition and by the physical properties of regolith at the CBVC.

Variability classes in the enigmatic black hole candidate GRS 1915+105 are known to be correlated with the variation of the Comptonizing Efficiency (CE) which is defined to be the ratio between the number of power-law (hard) photons and seed (soft) photons injected into the Compton cloud. Similarities of light curves of several variability classes of GRS 1915+105 and IGR 17091-3624, some of which are already reported in the literature, motivated us to compute CE for IGR 17091-3624 as well. We find that they are similar to what were reported earlier for GRS 1915+105, even though masses of these objects could be different. The reason is that the both the sizes of the sources of the seed photons and of the Comptonizing corona scale in the same way as the mass of the black hole. This indicates that characterization of variability classes based on CE is likely to be black hole mass independent, in general.

We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years.

The objective of the Shoal Harbor/Compton Creek Project was to evaluate proposed dredged material from the Shoal harbor/Compton Creek Project Area in Belford and Monmouth, New Jersey to determine its suitability for unconfined ocean disposal at the Mud Dump Site. This was one of five waterways that the US Army Corps of Engineers- New York District requested the Battelle Marine Sciences Laboratory (MSL) to sample and evaluate for dredging and disposal in May 1995. The evaluation of proposed dredged material from the Shoal Harbor/Compton Creek Project area consisted of bulk chemical analyses, chemical analyses of dredging site water and elutriate, benthic and water-column acute toxicity tests and bioaccumulation studies. Eleven core samples were analyzed or grain size, moisture content, and total organic carbon. Other sediments were evaluated for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl (PCB) congers, polynuclear aromatic hydrocarbons, and 1,4- dichlorobenzene. Dredging site water and elutriate water were analyzed for metals, pesticides, and PCBs.

The Compton Spectrometer and Imager (COSI) is a balloon-borne soft gamma-ray (0.2-5 MeV) telescope designed to perform wide-field imaging, high-resolution spectroscopy, and novel polarization measurements of astrophysical sources. COSI employs a compact Compton telescope design, utilizing 12 cross-strip germanium detectors to track the path of incident photons, where position and energy deposits from Compton interactions allow for a reconstruction of the source position in the sky, an inherent measure of the linear polarization, and significant background reduction. The instrument has recently been rebuilt with an updated and optimized design; the polarization sensitivity and effective area have increased due to a change in detector configuration, and the new lightweight gondola is suited to fly on ultra-long duration flights with the addition of a mechanical cryocooler system. COSI is planning to launch from the Long Duration Balloon site at McMurdo Station, Antarctica, in December 2014, where our primary science goal will be to measure gamma-ray burst (GRB) polarization. In preparation for the 2014 campaign, we have performed preliminary calibrations of the energy and 3-D position of interactions within the detector, and simulations of the angular resolution and detector efficiency of the integrated instrument. In this paper we will present the science goals for the 2014 COSI campaign and the techniques and results of the preliminary calibrations.

The Compton Spectrometer and Imager (COSI), formerly known as the Nuclear Compton Telescope (NCT), is a balloon-borne soft gamma-ray telescope (0.2-5 MeV) designed to study astrophysical sources of nuclear-line emission and gamma-ray polarization. The heart of COSI is a compact array of cross-strip germanium detectors (GeDs), providing excellent spectral resolution ( 0.2 - 1 %) and the capability to track individual photon interactions with full 3D position resolution to 1.6 mm3. COSI is built upon considerable heritage from the previous NCT balloon instrument, which has flown successfully on two conventional balloon flights to date. The Crab Nebula was detected at a significance of 6σ in the second flight, which is the first reported detection of an astrophysical source by a compact Compton telescope. COSI has been upgraded from the previous NCT instrument to be an Ultra Long Duration Balloon (ULDB) payload, utilizing a new detector configuration optimized for polarization sensitivity and employing a mechanical cryocooler to remove consumables (LN2) for ULDB flights. The instrument is being integrated for a ULDB flight in December 2014 from Antarctica on a superpressure balloon. Here we will present the redesign of the instrument and our current progress in preparing for the flight.

Gamma-({gamma}{sup -}) ray beams of high average power and peak brightness are of demand for a number of applications in high-energy physics, material processing, medicine, etc. One of such examples is gamma conversion into polarized positrons and muons that is under consideration for projected lepton colliders. A {gamma}-source based on the Compton backscattering from the relativistic electron beam is a promising candidate for this application. Our approach to the high-repetition {gamma}-source assumes placing the Compton interaction point inside a CO{sub 2} laser cavity. A laser pulse interacts with periodical electron bunches on each round-trip inside the laser cavity producing the corresponding train of {gamma}-pulses. The round-trip optical losses can be compensated by amplification in the active laser medium. The major challenge for this approach is in maintaining stable amplification rate for a picosecond CO{sub 2}-laser pulse during multiple resonator round-trips without significant deterioration of its temporal and transverse profiles. Addressing this task, we elaborated on a computer code that allows identifying the directions and priorities in the development of such a multi-pass picosecond CO{sub 2} laser. Proof-of-principle experiments help to verify the model and show the viability of the concept. In these tests we demonstrated extended trains of picosecond CO{sub 2} laser pulses circulating inside the cavity that incorporates the Compton interaction point.

Nuclear material accountancy is of continuous concern for the regulatory, safeguards, and verification communities. In particular, spent nuclear fuel reprocessing facilities pose one of the most difficult accountancy challenges: monitoring highly radioactive, fluid sample streams in near real-time. The Multi-Isotope Process monitor will allow for near-real-time indication of process alterations using passive gamma-ray detection coupled with multivariate analysis techniques to guard against potential material diversion or to enhance domestic process monitoring. The Compton continuum from the dominant 661.7 keV 137Cs fission product peak obscures lower energy lines which could be used for spectral and multivariate analysis. Compton suppression may be able to mitigate the challenges posed by the high continuum caused by scattering. A Monte Carlo simulation using the Geant4 toolkit is being developed to predict the expected suppressed spectrum from spent fuel samples to estimate the reduction in the Compton continuum. Despite the lack of timing information between decay events in the particle management of Geant4, encouraging results were recorded utilizing only the information within individual decays without accounting for accidental coincidences. The model has been validated with single and cascade decay emitters in two steps: as an unsuppressed system and with suppression activated. Results of the Geant4 model validation will be presented.

The energy band from a few hundred keV to a few hundred MeV offers a unique window for studying both thermal and the non-thermal astrophysical processes. Important science can be gleaned from investigations of emission mechanisms and environments of the most extreme objects that populate this mostly unexplored energy range.The Compton-Pair Telescope (ComPair) is a next-generation mission concept building on the pioneering observations by COMPTEL, on the Compton Gamma-Ray Observatory, and the heritage of recent successful missions, such as Fermi-LAT, AGILE, AMS and PAMELA. With its capability of detecting both Compton-scattering events at lower energy and pair-production events at higher energy, ComPair can explore the energy regime from 0.2 keV to > 500 MeV with unprecedented sensitivity. We describe the concept of this wide-aperture instrument and discuss its power to address fundamental questions from a broad variety of astrophysical topics.

We present results from a ~55 ks long XMM-Newton observation of the obscured AGN, NGC 5643, performed in July 2009. A previous, shorter (about 10 ks) XMM-Newton observation in February 2003 had left two major issues open, the nature of the hard X-ray emission (Compton-thin vs. Compton-thick) and of the soft X-ray excess (photoionized vs. collisionally ionized matter). The new observation shows that the source is Compton-thick and that the dominant contribution to the soft X-ray emission is by photoionized matter (even if it is still unclear whether collisionally ionized matter may contribute as well). We also studied three bright X-ray sources that are in the field of NGC 5643. The ULX NGC 5643 X-1 was confirmed to be very luminous, even if more than a factor 2 fainter than in 2003. We then provided the first high-quality spectrum of the cluster of galaxies Abell 3602. The last source, CXOJ143244.5-442020, is likely an unobscured AGN, possibly belonging to Abell 3602.

We have designed a Compton Camera (CC) to image the bio-distribution of gamma-emitting radiopharmaceuticals in mice. A CC employs the 'electronic collimation', i.e. a technique that traces the gamma-rays instead of selecting them with physical lead or tungsten collimators. To perform such a task, a CC measures the parameters of the Compton interaction that occurs in the device itself. At least two detectors are required: one (tracker), where the primary gamma undergoes a Compton interaction and a second one (calorimeter), in which the scattered gamma is completely absorbed. Eventually the polar angle and hence a 'cone' of possible incident directions are obtained (event with 'incomplete geometry'). Different solutions for the two detectors are proposed in the literature: our design foresees two similar Position Sensitive Photomultipliers (PMT, Hamamatsu H8500). Each PMT has 64 output channels that are reduced to 4 using a charge multiplexed readout system, i.e. a Series Charge Multiplexing net of resistors. Triggering of the system is provided by the coincidence of fast signals extracted at the last dynode of the PMTs. Assets are the low cost and the simplicity of design and operation, having just one type of device; among drawbacks there is a lower resolution with respect to more sophisticated trackers and full 64 channels Readout. This paper does compare our design of our two-Hamamatsu CC to other solutions and shows how the spatial and energy accuracy is suitable for the inspection of radioactivity in mice.

We have designed a Compton Camera (CC) to image the bio-distribution of gamma-emitting radiopharmaceuticals in mice. A CC employs the "electronic collimation", i.e. a technique that traces the gamma-rays instead of selecting them with physical lead or tungsten collimators. To perform such a task, a CC measures the parameters of the Compton interaction that occurs in the device itself. At least two detectors are required: one (tracker), where the primary gamma undergoes a Compton interaction and a second one (calorimeter), in which the scattered gamma is completely absorbed. Eventually the polar angle and hence a "cone" of possible incident directions are obtained (event with "incomplete geometry"). Different solutions for the two detectors are proposed in the literature: our design foresees two similar Position Sensitive Photomultipliers (PMT, Hamamatsu H8500). Each PMT has 64 output channels that are reduced to 4 using a charge multiplexed readout system, i.e. a Series Charge Multiplexing net of resistors. Triggering of the system is provided by the coincidence of fast signals extracted at the last dynode of the PMTs. Assets are the low cost and the simplicity of design and operation, having just one type of device; among drawbacks there is a lower resolution with respect to more sophisticated trackers and full 64 channels Readout. This paper does compare our design of our two-Hamamatsu CC to other solutions and shows how the spatial and energy accuracy is suitable for the inspection of radioactivity in mice.

The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8° and 19.1°, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6° was determined for the same γ-ray energy.

Gamma- (γ-) ray beams of high average power and peak brightness are of demand for a number of applications in high-energy physics, material processing, medicine, etc. One of such examples is gamma conversion into polarized positrons and muons that is under consideration for projected lepton colliders. A γ-source based on the Compton backscattering from the relativistic electron beam is a promising candidate for this application. Our approach to the high-repetition γ-source assumes placing the Compton interaction point inside a CO2 laser cavity. A laser pulse interacts with periodical electron bunches on each round-trip inside the laser cavity producing the corresponding train of γ-pulses. The round-trip optical losses can be compensated by amplification in the active laser medium. The major challenge for this approach is in maintaining stable amplification rate for a picosecond CO2-laser pulse during multiple resonator round-trips without significant deterioration of its temporal and transverse profiles. Addressing this task, we elaborated on a computer code that allows identifying the directions and priorities in the development of such a multi-pass picosecond CO2 laser. Proof-of-principle experiments help to verify the model and show the viability of the concept. In these tests we demonstrated extended trains of picosecond CO2 laser pulses circulating inside the cavity that incorporates the Compton interaction point.

The assumption behind impulse approximation (IA) for Compton scattering is that the momentum transfer q is much greater than the average < p > of the initial bound state momentum distribution p. Comparing with S-matrix results, we find that at relativistic incident photon energies (ωi) and for high Z elements, one requires information beyond < p > / q to predict the accuracy of relativistic IA (RIA) diferential cross sections. The IA expression is proportional to the product of a kinematic factor Xnr and the symmetrical Compton profile J, where Xnr = 1 + cos2 θ (θ is the photon scattering angle). In the RIA case, Xnr, independent of p, is replaced by Xrel (ω , θ , p) in the integrand which determines J. At nr energies there is virtually no RIA error in the position of the Compton peak maximum (ωfpk) in the scattered photon energy (ωf), while RIA error in the peak magnitude can be characterized by < p > / q . This is because at low ωi, the kinematic effects described by S-matrix (also RIA) expressions behave like Xnr, while in relativistic regimes (high ωi and Z), kinematic factors treated accurately by S-matrix but not RIA expressions become significant and do not factor out.

Ultra Luminous X-ray sources (ULXs) are unusually luminous point sources located at arms of spiral galaxies, and are candidates for the intermediate mass black holes (Makishima+2000). Their spectra make transition betweens power-law shapes (PL state) and convex shapes (disk-like state). The latter state can be explained with either the multi-color disk (MCD)+thermal Comptonization (THC) model or a Slim disk model (Watari+2000). We adopt the former modeling, because it generally gives physically more reasonable parameters (Miyawaki+2009). To characterize the ULXs spectra with a unified way, we applied the MCD+THC model to several datasets of ULXs obtained by Suzaku, XMM-Newton, and Nu-Star. The model well explains all the spectra, in terms of cool disk (T_{in}˜0.2 keV), and a cool thick (T_{e}˜2 keV, τ ˜10) corona. The derived parameters can be characterized by two new parameters. One is Q≡ T_{e}/T_{in} which describes balance between the Compton cooling and gravitational heating of the corona, while the other is f≡ L_{raw}/L_{tot}, namely, the directly-visible (without Comptonization) MCD luminosity. Then, the PL state spectra have been found to show Q˜10 and f˜0.7, while those of the disk-like state Q˜ 3 and f≤0.01. Thus, the two states are clearly separated in terms of Q and f.

Purpose: Ionization chambers in electron radiation fields are known to exhibit polarity effects due to Compton currents. Previously we have presented a unique manifestation of this effect observed with a microionization chamber. We have expanded that investigation to include three micro-ionization chambers commonly used in radiation therapy. The purpose of this project is to determine what factors influence this polarity effect for micro-chambers and how it might be mitigated. Methods: Three chambers were utilized: a PTW 31016, an Exradin A-16, and an Exradin A- 26. Beam profile scans were obtained on a Varian TrueBeam linear accelerator in combination with a Wellhofer water phantom for 6, 9, and 12 MeV electrons. Profiles were obtained parallel and perpendicular to the chamber's long axis, with both positive and negative collecting bias. Profiles were obtained with various chamber components shielded by 5 mm of Pb at 6 MeV to determine their relative contributions to this polarity effect. Results: The polarity effect was observed for all three chambers, and the ratio of the polarity effect for the Exradin chambers is proportional to the ratio of chamber volumes. Shielding the stem of both Exradin chambers diminished, but did not remove the polarity effect. However, they demonstrated no out-of-field effect when the cable was shielded with Pb. The PTW chamber demonstrated a significantly reduced polarity effect without any shielding despite its comparable volume with the A-26. Conclusions: The sensitive volume of these micro-chambers is relatively insensitive to collecting polarity. However, charge deposition within the cable can dramatically alter measured ionization profiles. This is demonstrated by the removal of the out-of-field ionization when the cable is shielded for the Exradin chambers. We strongly recommend analyzing any polarity dependence for small-volume chambers used in characterization of electron fields.

Compton scattering of photons by nonrelativistic particles is thought to play an important role in forming the radiation spectrum of many astrophysical systems. Here we derive the time-dependent photon kinetic equation that describes spontaneous and induced Compton scattering, as well as absorption and emission by static and moving media, the corresponding radiative transfer equation, and their zeroth and first angular moments, both in the system frame and in the frame comoving with the medium. We show that it is necessary to use the correct relativistic differential scattering cross section in order to obtain a photon kinetic equation that is correct to first order in Epsilon/m(sub e), T(sub e)/m(sub e), and V, where Epsilon is the photon energy, T(sub e) and m(sub e) are the electron temperature and rest mass, and V is the electron bulk velocity in units of the speed of light. We also demonstrate that the terms in the radiative transfer equation that are second order in V should usually be retained, because if the radiation energy density is sufficiently large, compared to the radiation flux, the effects of bulk Comptonization described by the terms that are second order in V can be as important as the effects described by the terms that are first order in V, even when V is small. The system- and fluid-frame equations that we derive are correct to first order in Epsilon/m(sub e). Our system-frame equations, which are correct to second order in V, may be used when V is not too large. Our fluid-frame equations, which are exact in V, may be used when V approaches 1. Both sets of equations are valid for systems of arbitrary optical depth and can therefore be used in both the free-streaming and diffusion regimes. We demonstrate that Comptonization by the electron bulk motion occurs whether or not the radiation field is isotropic or the bulk flow converges and that it is more important than thermal Comptonization if V(sup 2) is greater than 3T(sub e)/m(sub e).

A method of estimating and correcting for the magnetic field of a dual spinning spacecraft has been developed by employing an extension of the dual magnetometer technique. This new method is useful for those situations in which a magnetometer boom of modest length is attached to the spinning part of a large spacecraft. The purpose of using a dual spinning spacecraft is to accommodate two types of instruments: imaging and similar pointed remote sensing systems on the stationary platform, and fields, particles and other in-situ measuring instruments on the spinning portion. The new method assumes that the stationary part of the spacecraft possesses a magnetic field which is represented by a combination of a dipole and a quadrupole field.

This paper investigates which constraints can be placed on the fraction of Compton-thick active galactic nuclei (AGN) in the Universe from modelling the spectrum of the diffuse X-ray background (XRB). We present a model for the synthesis of the XRB that uses as input a library of AGN X-ray spectra generated by Monte Carlo simulations. This is essential to account for the Compton scattering of X-ray photons in a dense medium and the impact of that process on the spectra of heavily obscured AGN. We identify a small number of input parameters to the XRB synthesis code that encapsulate the minimum level of uncertainty in reconstructing the XRB spectrum. These are the power-law index and high-energy cutoff of the intrinsic X-ray spectra of AGN, the level of the reflection component in AGN spectra, and the fraction of Compton-thick AGN in the Universe. We then map the volume of the space allowed to these parameters by current observational determinations of the XRB spectrum in the range 3-100 keV. One of the least-constrained parameters is the fraction of Compton-thick AGN. Statistically acceptable fits to the XRB spectrum at the 68% confidence level can be obtained for Compton-thick AGN fractions in the range 5-50%. This is because of degeneracies among input parameters to the XRB synthesis code and uncertainties in the modelling of AGN spectra (e.g. level of reflection fraction). The most promising route for constraining the fraction of Compton-thick AGN in the Universe is via the direct detection of those sources in high-energy (≳ 10 keV) surveys. We show that the observed fraction of Compton-thick sources identified in the Swift/BAT serendipitous survey limits the intrinsic fraction of Compton-thick AGN, at least at low redshift, to 10-20% (68% confidence level). We also make predictions on the number density of Compton-thick sources that current and future X-ray missions are expected to discover. Testing those predictions with data will place tight constraints on

A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

Dual-energy CT imaging has many potential uses in abdominal imaging. It also has unique requirements for protocol creation depending on the dual-energy scanning technique that is being utilized. It also generates several new types of images which can increase the complexity of image creation and image interpretation. The purpose of this article is to review, for rapid switching and dual-source dual-energy platforms, methods for creating dual-energy protocols, different approaches for efficiently creating dual-energy images, and an approach to navigating and using dual-energy images at the reading station all using the example of a pancreatic multiphasic protocol. It will also review the three most commonly used types of dual-energy images: "workhorse" 120kVp surrogate images (including blended polychromatic and 70 keV monochromatic), high contrast images (e.g., low energy monochromatic and iodine material decomposition images), and virtual unenhanced images. Recent developments, such as the ability to create automatically on the scanner the most common dual-energy images types, namely new "Mono+" images for the DSDECT (dual-source dual-energy CT) platform will also be addressed. Finally, an approach to image interpretation using automated "hanging protocols" will also be covered. Successful dual-energy implementation in a high volume practice requires careful attention to each of these steps of scanning, image creation, and image interpretation.

A dual approximation for the solution to an optimal control problem is analyzed. The differential equation is handled with a Lagrange multiplier while other constraints are treated explicitly. An algorithm for solving the dual problem is presented.

Co-occurrence of mental disorders and substance use disorders (dual diagnosis) among doctors is a cause of serious concern due to its negative personal, professional, and social consequences. This work provides an overview of the prevalence of dual diagnosis among physicians, suggests a clinical etiological model to explain the development of dual diagnosis in doctors, and recommends some treatment strategies specifically for doctors. The most common presentation of dual diagnosis among doctors is the combination of alcohol use disorders and affective disorders. There are also high rates of self-medication with benzodiazepines, legal opiates, and amphetamines compared to the general population, and cannabis use disorders are increasing, mainly in young doctors. The prevalence of nicotine dependence varies from one country to another depending on the nature of public health policies. Emergency medicine physicians, psychiatrists, and anaesthesiologists are at higher risk for developing a substance use disorder compared with other doctors, perhaps because of their knowledge of and access to certain legal drugs. Two main pathways may lead doctors toward dual diagnosis: (a) the use of substances (often alcohol or self-prescribed drugs) as an unhealthy strategy to cope with their emotional or mental distress and (b) the use of substances for recreational or other purposes. In both cases, doctors tend to delay seeking help once a problem has been established, often for many years. Denial, minimization, and rationalization are common defense mechanisms, maybe because of the social stigma associated with mental or substance use disorders, the risk of losing employment/medical license, and a professional culture of perfectionism and denial of emotional needs or failures. Personal vulnerability interacts with these factors to increase the risk of a dual diagnosis developing in some individuals. When doctors with substance use disorders accept treatment in programs

Communities of Purpose are commonly known to enact their purposes through social movements, grassroots efforts, semi-formal groups, and through organizations in the voluntary sector. They carry out charitable missions and goals and are often committed to the pursuit of social welfare and social change. In this research, I explain why Communities…

A dual beam interferometer device is disclosed that enables moving an optics module in a direction, which changes the path lengths of two beams of light. The two beams reflect off a surface of an object and generate different speckle patterns detected by an element, such as a camera. The camera detects a characteristic of the surface.

Generalized Parton Distributions (GPDs), introduced in the late 90s, provide a universal description of hadrons in terms of the underlying degrees of freedom of Quantum Chromodynamics: quarks and gluons. GPDs appear in a wide variety of hard exclusive reactions and the advent of high luminosity accelerator facilities has made the study of GPDs accessible to experiment. Deeply Virtual Compton Scattering (DVCS) is the golden process involving GPDs. The first dedicated DVCS experiment ran in the Hall A of Jefferson Lab in Fall 2004. An electromagnetic calorimeter and a plastic scintillator detector were constructed for this experiment, together with specific electronics and acquisition system. The experiment preparation, data taking and analysis are described in this document. Results on the absolute cross section difference for opposite beam helicities provide the first measurement of a linear combination of GPDs as a function of the momentum transfer to the nucleon.

Purpose: Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors present a fast and simple method by which to generate an initial back-projected image from acquired CCI data, suitable for use in a filtered back-projection algorithm or as a starting point for iterative reconstruction algorithms, and compare its performance to the current state of the art. Methods: Each detector event in a CCI system describes a conical surface that includes the true point of origin of the detected photon. Numerical image reconstruction algorithms require, as a first step, the back-projection of each of these conical surfaces into an image space. The algorithm presented here first generates a solution matrix for each slice of the image space by solving the intersection of the conical surface with the image plane. Each element of the solution matrix is proportional to the distance of the corresponding voxel from the true intersection curve. A threshold function was developed to extract those pixels sufficiently close to the true intersection to generate a binary intersection curve. This process is repeated for each image plane for each CCI detector event, resulting in a three-dimensional back-projection image. The performance of this algorithm was tested against a marching algorithm known for speed and accuracy. Results: The threshold-based algorithm was found to be approximately four times faster than the current state of the art with minimal deficit to image quality, arising from the fact that a generically applicable threshold function cannot provide perfect results in all situations. The algorithm fails to extract a complete intersection curve in image slices near the detector surface for detector event cones having axes nearly

Background: Physician dual practice is a common phenomenon in almost all countries throughout the world, which could potential impacts on access, equity and quality of services. This paper aims to review studies in physician dual practice and categorize them in order to their main objectives and purposes. Methods: Comprehensive literature searches were undertaken in order to obtain main papers and documents in the field of physician dual practice. Systematic searches in Medline and Embase from 1960 to 2013, and general searches in some popular search engines were carried out in this way. After that, descriptive mapping review methods were utilized to categorize eligible studies in this area. Results: The searches obtained 404 titles, of which 81 full texts were assessed. Finally, 24 studies were eligible for inclusion in our review. These studies were categorized into four groups - “motivation and forces behind dual practice”, “consequences of dual practice”, “dual practice Policies and their impacts”, and “other studies” - based on their main objectives. Our findings showed a dearth of scientifically reliable literature in some areas of dual practice, like the prevalence of the phenomenon, the real consequences of it, and the impacts of the implemented policy measures. Conclusion: Rigorous empirical and evaluative studies should be designed to detect the real consequences of DP and assess the effects of interventions and regulations, which governments have implemented in this field. PMID:27141489

A nearby superluminous burst GRB 130427A was simultaneously detected by six γ-ray space telescopes (Swift, the Fermi GLAST Burst Monitor (GBM)/Large Area Telescope, Konus-Wind, SPI-ACS/INTEGRAL, AGILE, and RHESSI) and by three RAPTOR full-sky persistent monitors. The isotropic γ-ray energy release is ~1054 erg, rendering it the most powerful explosion among gamma-ray bursts (GRBs) with a redshift z <= 0.5. The emission above 100 MeV lasted about one day, and four photons are at energies greater than 40 GeV. We show that the count rate of 100 MeV-100 GeV emission may be mainly accounted for by the forward shock synchrotron radiation and the inverse Compton radiation likely dominates at GeV-TeV energies. In particular, an inverse Compton radiation origin is favored for the ~(95.3, 47.3, 41.4, 38.5, 32) GeV photons arriving at t ~ (243, 256.3, 610.6, 3409.8, 34366.2) s after the trigger of Fermi-GBM. Interestingly, the external inverse Compton scattering of the prompt emission (the second episode, i.e., t ~ 120-260 s) by the forward-shock-accelerated electrons is expected to produce a few γ-rays at energies above 10 GeV, while five were detected in the same time interval. A possible unified model for the prompt soft γ-ray, optical, and GeV emission of GRB 130427A, GRB 080319B, and GRB 090902B is outlined. Implications of the null detection of >1 TeV neutrinos from GRB 130427A by IceCube are discussed.